Category Archives: Reloading Corner

Reloaders Corner: Coated Bullets

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Bullet coatings promise better performance, but are they the right choice for you? Find out.


Glen Zediker


There are a few bullet coatings available, and Moly (MoS2: molybdenum-disulfide) is the best known, and also the most notorious. More in a bit.

moly coated bulets
Molybdenum Disulfide is the most popular bullet coating. It has exceedingly positive effects on performance, but there are may be some serious consequences for the uninformed user. Without correct (and frequent) cleaning, it can cause long-term damage to a barrel. Use it as outlined in this article and the extra speed and improved accuracy can pay back big to a serious shooter.

First, here’s how and why bullet coating works: Fire a coated bullet and a bare bullet using the same propellant charge. The coated bullet will go slower. However. The pressure will be lower. The reason is easy to figure: the increased lubrication reduces friction, resistance to movement, especially upon entry into the bore. It gets kind of a head start. The deal is that the pressure drops relatively more than the bullet speed, so, the bullet speed can be increased by adding more propellant and still have the same level of pressure. Win. Win. And, since there’s what amounts to a barrier between the bullet jacket and the barrel steel, the promise of more accurate rounds between cleanings is all true too. The bullet jacket isn’t leaving much of itself behind on the bore.

Among competitive shooters there was a huge shift toward coated bullets a few years back, but they’ve since fallen from favor for many. It wasn’t because they don’t perform well, because they do, but there are ancillary, and important, liabilities. Mostly: moly-coated bullets can corrode barrel steel, including stainless. Molybdenum disulfide outgases (outgas is the release of an occluded gas vapor that was part of the compound; a state change, pretty much) at temperatures lower than firing temperatures, and that creates a residue that, when mixed with water (moisture from condensation included, like what happens after firing), is pretty much sulfuric acid. Yikes. Right. If a moly-coated barrel is cleaned (correctly) each use, no problems. But one of the big draws is the potential to get literally hundreds of rounds, on zero, before the barrel needed cleaning. After a conventional cleaning (solvent and brush) it also takes time, which is rounds through the barrel, before zero will return.

I am a fan of coated bullets, and they’ve convincingly demonstrated their superiority to me after many thousands of rounds reaping rewards from the ballistic advantages. The improvement can be significant, and some bullets in particular escalate in performance more than others. Shorter bearing surface designs, by my notes, get that much more additional speed with no pressure trade-offs. Coating seems to have a disproportionately positive effect on thinner-skinned bullets, for reasons that likewise are clear. The effect here is smaller group sizes. Anything with a “J4” jacket responds well to coating (common in custom bullets).

My solution to the worries about moly was, as suggested, simply to clean the barrel each time back from the range and, also, to change my cleaning method to better accommodate the residue composition. More in a bit.

I don’t use moly any more, though. I’ve switched to Boron Nitride (BN) because it has all the advantages with none of the drawbacks, so far. BN is virtually the same in its effects as moly, based on my notes (same level of velocity drop and subsequent future increase). It’s easy to apply using a vibratory-style case cleaner.

BN coated bullet
This is a Boron-Nitride-coated bullet (right) compared to a bare bullet. BN is clear, slick, and doesn’t cause the chemical reactions other coatings are notorious for. It’s what I use.

I do not recommend any sort of lubrication inside a barrel, not for a promise of increased bullet performance. PFTE, for instance, has been touted as a great “break-in” agent for a barrel. Some use it after each cleaning to prep a barrel. Well. When it outgases, and it does outgas, it releases fluorine, a very powerful eater of all things metal.

Cleaning: Don’t use copper solvent with moly! The ingredients don’t mix well. Use only petroleum-based solvent. I switched to Kroil pentrating oil in conjuction with something like USP Bore Paste, JB Bore Compound, or similar (abrasive paste-type formulations). No room here now to convince anyone that abrasives are a safe and wise choice, but used correctly they are both. “Correctly” means a rod guide, stainless-steel rod, and keeping the rod shaft clean each pass. With that combination the bore is being protected against corrosion and the residues get gone, and, of huge importance, zero returns right away.

moly coated barrel cleaning
Bullet coating leaves an entirely different residue that conventional cleaners might not be effective on, and there’s also some chemistry involved that can inadvertently create big problems. I’ve had best results, all around, with a combination of micro-penetrating oil and abrasive paste. Keep the rod clean and feed it through a rod guide using abrasives and there’ll be no damage done.

Last on this: Just in the same as how I do not recommend “mixing” bullets or propellants through the same barrel, same day, coatings are pretty much the same. Zero will, not can, change for the number of rounds it takes to “re-season” the barrel. If you use it, use it.

I’ve seen great gaps in the quality of coated bullet finishes. Factory-coated bullets are the way to go. It’s tough to get a good job at home, and the reason is the carnuba wax application is temperature sensitive, and also because commercial coaters use industrial-level tumblers to apply the powder. The wax is necessary to avoid a smudgy mess just from handling the bullets. If you want to do it yourself, make sure the bullets are cleaned before application. Likewise, moly can build up in a bullet seating die so clean it out every now and again.

BN Coating Kit
BN can be applied easily using a vibratory tumbler and the contents shown. Put the BN powder in the bottle with the bullets, run the bottle in a vibratory cleaner for a spell, and that’s that. Check HERE for more information on bullet coating.

The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com

Reloaders Corner: Outside Case Neck Turning

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For the perfectionist! Here’s a look at an often misunderstood and widely feared case-preparation step. It’s really not all that bad! Keep reading to learn what and why.


Glen D. Zediker


Outside cartridge case neck turning is a bench-top machine-shop-style operation. It is the only way to substantively improve case neck wall consistency. This is done via material removal using an outside case neck turning appliance. The outside neck turner shaves down the “high spots” around the neck circumference. That makes the neck walls more uniform in thickness. It’s a cutter and a gap, and that gap determines the case neck wall thickness. It’s finite.

neck turner
An outside neck turning tool, most of them, use a mandrel that’s inserted into the case neck. A cutting blade is then lowered onto the neck outside, adjusted for the amount (depth) of cut, and then is run around and around, going down the case neck a little each turn, shaving this amount of material from the surface. Like a carpenter’s plane. The slower you go the less the case neck will look like an LP.

It’s pretty well agreed on and accepted that concentric relationships mean better accuracy. Getting the bullet sitting dead center in a rifle bore means that the case neck must be “straight.” A “straight” case neck results from consistent neck wall thickness. And that’s because inconsistent wall thickness creates an off-center case neck cylinder when the bullet is seated. Consistent neck walls result in a center that’s concentric (if the tooling supports it).

This is a tedious ticky operation. If you are going to turn case necks, get what you think you are from it. The only tools I’ve used thus far that do a precise job of this op are the “hand-held” turners. The lower degree of tolerance is, as with many things, the reason. A tight fit between the mandrel that goes inside the case neck and the case neck inside diameter makes for a more precise operation. The mandrel and the cutter gap will be consistent and precisely adjustable; therefore, so too will be the resultant wall thickness. The first step is to size the case neck with an expanding mandrel to fit the mandrel on the turner. The higher-speed tools, such as those that operate under power or via a crank-style base rely on some other means to locate and fix the center of the case neck. That’s not to say better is not better, because it always is. Again, it’s degrees.

Use new brass!

I have a Gracey power turner that works so fast there no real reasons not to use it for every case. It, yes, without a doubt can make a case neck better. The Forster neck turning attachment that fits the Forster trimmer base unit (same used for case trimming, and other ops) fits the same description, as does the Horndady LNL tool. These are fast enough and easy enough, and the investment will improve wall thickness uniformity. Point is, if you want to turn each case neck you choose to 0.0095 inches, you’ll need a hand tool. And a micrometer. And time. With a hand tool, the job itself is not terribly difficult or slow, but adding in the initial neck sizing op and then another sizing afterward with the usual die, it’s steps.

Hornady LNL Neck Turner
As with many things, there’s a speed/quality tradeoff choosing an outside case neck turner. For my money, and time, I choose to go with a hand-held tool to get the most from the time I spend. I don’t turn all the cases, only the ones I’ve segregated into my “600-yard pile.” A good crank-style turner is the way to go for someone who wants to just run them all through. They’re faster but not usually as precise. This is a Hornady LNL Neck Turner, and it’s a great choice.

There’s a good question to answer and it involves the tolerance you’re willing to accept: perfection has a price. If the cutter head is adjusted to remove metal from the entire surface of the case neck, that means the wall thickness will be universally reduced. And that means you’ll now need to examine and possibly change your sizing setup to regain adequate post-sizing dimensions to secure a bullet. Using a routine sizer, the neck cylinder outside will get reduced to the same diameter as a case with thicker neck walls, but the case neck inside diameter will be larger because the walls are thinner. Depending on the expander diameter used in the die, the net result might be a case neck that retains an overly-large i.d. It’s just math. But make sure you work the numbers though.

Forster neck turning tool
To get the most precision from outside neck turning the case neck inside diameter must closely match the mandrel or pilot diameter on the neck turning tool. Lubrication helps! I use engine assembly lube gotten from a good auto parts store. Lube the case neck inside. You might have to adjust the sizing dimension to get this fit; some systems allow sizing with the same mandrel to get a close match. Cases should be sized and trimmed prior to the neck turning process, and then sized again afterward. Here’s a Forster hand-held tool.

I never aim to turn the full circumference surface area around a case neck. The reason is that means adjusting the tool to produce thinner than “blueprints.” The idea, for me, is to erase the inconsistencies that remain in my sorted brass: clean them up. For example, let’s say that, after measuring enough places on enough cases, I determine that a brass manufacturer intended this tubing to be 0.011 inches (that was the “blueprint”), that then defines the cutting depth limit I’ll set my turner to deliver.

If you do turn case necks, make sure to continue cutting a little ways down onto the case shoulder (if the cutter design allows this, it needs to have an angle incorporated for this purpose). This helps stay off the formation of a case neck donut. Works wonders.

partially turned case neck
Here’s how my cases look after neck turning. A little splotchy, but my goal is not a universal reduction of wall thickness, just “better is better.” So instead of a case being over 0.001 out of spec, now it’s about 0.0005 variation, but decidedly not perfect. Those with the smallest visible cut area were better from the start. I do this way mostly to preserve the sizing die dimensions and effect the same on all my brass. Thinner neck walls tend to crack easier, so it’s safe enough to say that, with a standard-type rifle chamber (not done with a “tight-necked” Benchrest-style reamer) case life will shorten. Notice the shoulder cut. Removing a little material from this area alleviates case neck donuts.

Check out neck turning tools at Midsouth. CLICK HERE.


The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com

Reloaders Corner: AR15 Chamber Options

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It’s vital to understand “which” chamber is in your AR15. What you don’t know can create big problems. Here’s why.


Glen Zediker


I’ve talked over or at least touched upon this topic, here and there, in other articles. And this week I got four phone calls asking for advice on “which” AR15 chamber I’d recommend. I guess that sort of spurred creation of this article. My primary goal (always) is to answer questions, and ideally before they are asked. So…

NATO mark
A TRUE NATO load always has this mark on its base: the cross-in-a-circle stamp. Some commercial ammo that appears to be mil-spec may or may not be, but err on the safe side.

There are a few options today, and, no, it never was “simple.” There have always been two distinct chambers cut for .223 Remington and 5.56x45mm NATO. And that’s the difference right there! See, .223 Rem. is a commercial round, 5.56 is a mil-spec round. Yes. They are “the same,” but they’re not. The difference is in how these two are loaded with respect to pressures. NATO is a whopping lot hotter. To the tune of +15,000 PSI.

The differences in the chambers are, pretty much, that a NATO has a significantly longer throat or leade or freebore, whichever term is preferred. This is the area in a chamber that extends beyond the case neck cut.

Chamber-All gage
I use a Hornady LNL OAL gage to find out exactly the length of the chamber throat. Get one at Midsouth. This read shows “NATO” by the way. Sierra 80gr MatchKing at 2.550 inches to touch the lands. Wylde should read 2.475. SAAMI-minimum will (usually) be 2.395.

This area in a chamber accepts the initial gas expansion, so, in one way, it can be looked at like an expansion chamber. More room for expanding gases effectively reduces stress on the case. When this area is lengthened, there’s more room, less pressure build. When this area is shortened, there’s less room, more pressure build.

As said, .223 Rem. is short, NATO is long. Take a NATO-spec round and fire it in a .223 Rem. chamber and there’s too much pressure. The .223 Rem. will “fit” just fine; there’s no influential differences otherwise in chambering specifications between .223 Rem. and 5.56.

You’ve probably heard all that before. It’s very important to know. “Which” chamber affects making loaded ammo choices, and also in interpreting reloading data.

NATO pressure
Here’s “real” NATO fired in a commercial .223 Rem. chamber. Ouch. The imprints and general beating the case head shows are the result of the additional pressure in the NATO loading, and the .223 Rem. chamber’s inability to excuse that much extra pressure.

Short history as to the reasons these two chambers exist: .223 Rem. in civilian, commercial application was a varminting-type round, along the lines of .222 Rem. When SAAMI (Sporting Ammunition and Arms Manufacurers Institute) laid down the specifications for that round it did so based around the prevalent short .224 bullets of the day, which were often 52-grain flatbase designs. For best accuracy with the little bullets, the throat was kept short, decreasing the distance the bullet had to travel to engage the lands or rifling. Some, most, me included, call this chamber a “SAMMI-minimum.” The mil-spec ammo assembled for M16s used a 55-grain boat-tail loaded to a higher velocity, and the longer throat was specified to handle the extra gas.

What matters is knowing that you don’t have a .223 Rem. chamber. A NATO can handle anything.

Most AR15s I’ve handled in the past good long while have NATO chambers. It’s the only thing that makes any sense for someone, anyone, who wants to fire sto-bot ammo. Not all the mil-type commercial loads (like the “white box” varieties) are true NATO spec, but if the ammo is not marked “.223 Rem.” it might be a tad amount to a lot hotter than a short-throated gun should handle. True NATO ammo has a distinct marking on the case base.

There is now another what’s become “standard” chamber for AR15s, and that’s the Wylde. Named for AR15 accuracy pioneer Bill Wylde, this reamer specs fall between SAAMI-minimum and NATO. Bill started cutting these chambers for NRA High Power Rifle contestants who needed more room in the throat to accept the long 80-grain bullets but not so much room that the shorter 69-grain bullets were having to leap a gorge to engage the lands. A compromise. A Wylde is a good chamber, and a good choice.

Compare .223 chambers
Here’s the best way to see what’s going on with AR15 chambers. These are Sierra 80-grain MatchKing bullets loaded to an overall cartridge length that has the bullet touching the rifling. Left to right: SAMMI-minimum .223 Rem.; Wylde; NATO. Wahoo. Big, big differences. There’s a little more than 0.150 inches between the SAAMI-minimum and the NATO and that space in the throat handles the extra PSI of NATO-spec loadings. It is also, by the way, how to know (or one way to know) the actual “length” of a chamber throat.

Here’s how it breaks down, according to me:
SAAMI-minimum or commercial .223 Rem. chamber is good for those who are wanting the best accuracy from light bullets. Can’t run mil-surplus ammo or NATO-spec commercial though.

NATO is for anyone who wants to shoot anything and everything out there safely.

NATO stamp
There’s a few ways I’ve seen “NATO” marked on barrels, and I’ve seen a good number of barrels that aren’t marked at all. That’s terribly irresponsible. Look for “5.56” since that seems to have become the more common way to denote “NATO.”

Wylde is more or less an “Improved NATO,” and my experience has been that it will safely handle true NATO loads, even if that’s not its intended design. I base that on spent case condition. It will shoot a little better than a NATO with lighter, shorter bullets. The Wylde is available more and more commonly now from different manufacturers and in “drop-in” accessory barrels.

winchester .223 ammo
If you have a “.223 Rem.” stamp on your barrel don’t feed it any ammo that is not clearly likewise marked “.223 Rem.” Should say the same on the case headstamp. If it doesn’t read “.223 Rem.” do not fire it in a barrel stamped “.223 Rem.” This ammo is safe for any AR15. If you don’t see a stamp on your barrel, find out…or just fire .223 Rem.

The preceding was adapted from Glen’s newest book, Top-Grade Ammo, available here at Midsouth. For more information on this book, and others, plus articles and information for download, visit ZedikerPublishing.com

Reloaders Corner: Case Trimming: finishing the job

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So you have a sack full of trimmed cases. Now what? Here’s what! A few tips on final preparation that may even promote better accuracy. Keep reading…


Glen Zediker


The most basic and necessary tool or tools we’ll need to get the freshly-trimmed case into shape to take on a new bullet is an “outside” and “inside” chamerfing appliance. These are most popularly housed in one hand-held tool: one end does the outside and the other does the inside. Of course (of course) there are options, and some are right dandy.

LE Wilson chamfer tool
Here’s a basic and common LE Wilson inside/outside chamfering too. One end does the outside, the other does the inside. Shown is a 45-degree tool.

After trimming the case mouths will be square, flat, and appear wider-walled than before. That’s normal.

There will usually be a little edge-ring of brass on the exterior surface of the case neck, and that’s the reason for the wider appearance. That’s easily remedied. It takes only a light skiff using the “outside” function of the tool.

trimming burr
That little ring of brass around the top outside edge of the case neck: just get it gone. Doesn’t require a cut, just a skiff with an outside deburring tool.

Don’t cut into the outside, just remove the ring. No bevel is necessary; that only thins the case mouth. If the ring is left standing, the case might not want to feed, and then there will be little shards of brass here and there.

Next, the inside. The inside edge of the case mouth needs to be broken and also beveled to more easily accept a bullet. Now we’ve got options in depth of the bevel and angle of the bevel.

The long-time “standard” is a 45-degree chamfer. That functions okay to allow most bullets to sit unsupported in the case neck prior to seating. I believe, and I’m not nearly alone, that a steeper angle is better. For anyone loading bullets that are of a longer, “spikier” form, I strongly recommend something closer to 30 degrees, or less. These are often called “VLD” cutters or chamfer tools, and that is because these tools followed the “low-drag” style bullets that, among other attributes, featured relatively longer, more steeply angled boat-tails. They also have relatively thinner jackets (“J4”). Essentially, a 45-degree pathway and the geometry on the bullet didn’t mate up.

Lyman VLD chamfer tool
Here’s a Lyman “VLD” chamfer tool. It’s got a 22-degree angle. I’ve used other brands that were 19 and 20, and I honestly don’t know that a couple degrees makes much difference. However! There’s a world of difference between this and a 45-degree tool.

The result of a greater angle mismatch is that the bullet gets a pretty hard start into the case neck, and it can also get a crooked start, and that’s because it’s not sitting “into” the neck very far. It’s in a precarious position and easily tilted. These long bullets create what amounts to more leverage in less-than-perfect case necks, which is going to be the most of our case necks unless we’re neck turning. (It’s also why I’m a big believer in a bullet-seating stem that engages farther down the bullet nosecone; this also helps reduce the angular deflection in seating.) I’ve seated and then pulled bullets from cases with 45- and 20-degree chamfers, for instance, and those from the shallower angle show noticeably less scuffing. (Plus, many of the custom-made low-drags feature a “pressure ring,” which is a tiny elevated ring right at the boat-tail/shank junction, usually about 0.0005 diameter, which helps obturation. That ring can get deformed by a 45-degree chamfer.)

It’s not the depth into the case neck cylinder that improves the transition into the case neck, so a “bigger” cut with a 45 won’t do a thing. A steeper cutter is going to make a deeper extension into the case neck simply because the angle is steeper.

Cutting the inside, do not go for a knife edge! For a yardstick, I suggest going about halfway on a 45-degree cut and 2/3 on a VLD-style chamfer tool. By that I mean that the appearance of the wall thickness at the case mouth is roughly half after chamfering that it was before.

Forster 3-way trimming head
There are also “all-in-one” cutter/chamfer/deburr heads for some case trimmers. These are one bugger to set up, but they work well and save a ton of time and extra steps, and since it’s incorporated into the length-trimming operation, the chamfer consistency will be spot-on. Trick is finding one that cuts a shallower angle on the inside… If not, it’s going to produce better results overall to do this operation separately.

It is important, at least in logical thought, to have the same chamfer depth on each case to ensure perfectly consistent engagement with the bullet shank. Honestly, I don’t know if that shows up on a target, but it’s easily attained using either an LE Wilson or Forster case trimming base, as well as some others, with the addition of a chamfering tool in the apparatus to replace the length trim cutter. It’s an extra step in retooling and adjustment, but then if the cases are all the same length and the stops are set, each case mouth will have an identical chamfer.

LE Wilson neck reamer
Here’s a trick and half for seating flat-base bullets. These are difficult to get started straight since there’s no boat-tail to ease transition into the case neck. I use an LE Wilson inside neck reamer set to engage a feature built into that tool. LE Wilson added a short tapered area that can be run into a sized case neck, about 1/16 inch, that machines something close to a “shelf” that provides a nest for the flat bullet base. There’s a noticeable improvement in runout on the flat-base bullets I have seated with and without this cut. [Note: This is the “standard” inside neck reamer intended to remove excessive thickness in the case neck cylinder on fired cases, not sized cases; the feature just described is an accessory benefit and, again, is engineered for use on sized case necks.]

The preceding is a specially-adapted excerpt from Glen Zediker’s newest book Top-Grade Ammo. Available right’chere at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, as well as others.

RELOADERS CORNER: Case Trimming

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Trimming bottleneck cartridges is a necessary chore, and here’s how to make it easier, and better…


rifle case trimmer
Case trimming is a needed step in the case-preparation process, and needs vary with the rifle type, and other factors. Don’t get obsessed with it, but don’t neglect it either. Not all case trimmers are equal. We’ll talk more about some I like next time, and I’ll tell you why.

At some point, now or later, bottleneck cartridges need to be trimmed. The reason is because brass flows in firing. After one or more firings and reloadings, a case will measure longer than it was when new. That extra length can only come off of the case mouth, and that’s why we trim cases. The case neck itself isn’t the main culprit in the growth, it’s just where we can address it. The most flow comes from lower down on the case.

The reason I said “now or later” is because the amount of lengthening varies from firearm to firearm and, generally, there’s usually a sooner need for trimming on a semi-auto than there will be on a bolt-action. There are two reasons for this: one is that the semi-auto will tend to expand a case more (and we’ve talked though a few reasons for that in previous articles). Another is that we’re having to full-length resize cases and set the case shoulders back a little more to ensure function. That works the brass more, no doubt. The brass is stretched more, it’s expanded and contracted more.

Important: The primary reason to trim cases is so they don’t get long enough to create a safety problem. That problem is when the case neck extends to a point where it contacts beyond its given space in the rifle chamber. That can pinch in against the bullet; excessive pressure results. The leeway will vary from chamber to chamber, and there’s no defined standard; there are plug-type gages available to measure a chamber if you want to know what you have.

case trimming
The primary reason to trim is to keep overly-long cases from overrunning their space in the chamber. If the case mouth encounters the end of its allotted space, it can pinch in on the bullet, elevating pressure. Now, there’s usually a good deal of leeway before safety can be a question, but don’t push it…

From a “performance” perspective, trimming cases should mean that all the case neck cylinders are the same height. If they’re not, then varying effective levels of bullet retention result (even if the sizing is all the same, more encasement can mean slower release).

Another is that a good trimmer will square case mouths. This is an asset to better starting alignment seating bullets and is especially and measurably noticeable using flat-base bullets.

Here’s what I do: When I get a new lot of brass, I set my trimmer so it just touches the case mouth. It takes a few tries to get this right, but the idea is that I want to see at least a skiff of a cut on each case, evidence that the trimmer contacted the case mouth. These cuts won’t all be even because not all the new case mouths will be square. Measure them all and you’ll likely see length discrepancies right off the bat. I want to eliminate those. Then I leave my trimmer set right there for future use. If we’re using the same trimmer for difference cartridges, keep a dummy case near to it and use that to reset the trimmer when there’s a tooling change. It might get expensive buying a trimmer for each cartridge you load for, but it’s sheer bliss never to have to retool a trimmer!

measuring case length
A caliper is the only tool needed to measure case length. It’s not really necessary to measure each and every case each and every time. It’s a whopping lot faster to set the trimmer so it just touches the shortest case you have (revealed through the process itself in setting up the trimmer) and trim all the cases using that setting locked in place. If it’s a fired case, make sure it’s been deprimed or the measurement won’t be accurate.

Now, there’s zero harm in using a longer “trim-to” length, and that’s way more popular than my method. These lengths are stated in reloading data manuals. Keeping up with it over years, I’ve seen no difference in the rate of lengthening trimming longer or shorter; I trim “shorter” solely as a matter of consistency over the (short) life of my semi-auto cases. Also, I trim all my cases, when I trim them. I don’t measure each case. I just trim them all. That’s overall faster and more certain.

Here’s a few things to always keep in mind about case trimming. One, and the most important in my process at least, is that the only time to trim a case accurately is after that case has been resized! That’s when there’s an accurate indication of case length. Measure a fired and un-sized case against one that’s fired and then sized, and the un-sized case very likely show a shorter length. That’s only because there’s been expansion in the case neck and body. As the expanded areas are brought back into spec by a sizing die it’s along the same lines as rolling a ball of modeling clay out on a table: it gets longer as it gets smaller in diameter.

trimmed case
A freshly trimmed case isn’t ready to go, yet, and we’ll fix all that next time too.

Also, only after sizing can we know that the case neck, case shoulder area is consistent in dimension. Measure enough of them and you’ll find some cases exhibit variance. We’re talking very small numbers here, but we’re always dealing with very small numbers, so let’s get them all the same. And that’s one of the virtues of trimming cases.

Next time more about the tools.


The preceding is a specially-adapted excerpt from Glen Zediker’s newest book Top-Grade Ammo. Visit ZedikerPublishing.com for more information, and BuyZedikerBooks.com to order.

Progressive Press Tricks

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Progressive reloading presses are amazing and efficient ammo-creating machines, and they’re not just for pistols! Here’s a few tips on getting the most from yours. You can find the Hornady Lock-N-Load Progressive Press at Midsouth Shooters by Clicking Here!


Glen Zediker


A “progressive” press is a wondrous thing.

This is a machine (only word that fits) that progresses through loading operation stations via a rotating shell plate (well, most rotate, but some commercially-oriented units move straight-line). This plate incorporates a ratcheting mechanism that indexes a cartridge case into alignment with the next tool station with each cycle of the press handle (some require manual index-advancement of the plate, but most can be had as “automatic”). Another case is added with each stroke, as is another bullet at that station, so after the plate has been filled with cases, a loaded round is ejected and an empty case is added each cycle, with each stroke of the press handle.

It’s a compact-sized bench-mounted ammo assembly line.

hornady progressive
It’s not right at all to call a progressive an “automated turret.” Turrets have a head that moves; progressives have a shell-holding plate that moves. And, there are other operations embodied in a good progressive design that simply cannot be replicated with an auto-indexing turret.

In a progressive, each operation — case sizing, priming, propellant dispensing, bullet seating, and even more — is supplied by a toolhead that has four or more tool-containing bodies corresponding to the openings on the shell plate. Priming is accomplished via a primer dispenser, which is usually a tube containing primers coupled with an means to locate each primer such that it will be seated on the handle upstroke (shell plate coming down); almost always, this is coincidental with full-length sizing. The propellant dispenser form varies, but is another automated process that is linked (literally) to the press handle stroke.

Progressive loading machines are complex, but they can be well-conceived, well-made appliances that perform reliably. Results are largely up to the operator. More about that in a bit.

The cost and complexity of a progressive (related) primarily reflect its level of automation. A “basic” progressive requires the operator to manually position an empty case at the first station, manually advance the shell plate, and place a bullet in each case mouth. The more complex, and costly, machines have case and bullet feeders, and warning systems that give notice of diminishing components.

Keep a close watch on supply levels! The efficiency of a good progressive can warp time… Running one of the “big” progressives I am always surprised how quickly the primer supply and powder meter hopper empty.

Keep the machine clean and lubricated. This eliminates most function issues. Think about what’s going on here and it’s easy to see that a well-maintained machine will be a reliable and consistent machine. Remember that all operations revolve around the revolution of the shell plate. Keep it clean and lubed appropriately.

Mount a progressive securely on a rigid base. There is a lot (a lot) of pressure and stress involved in cycling a progressive, especially a “big” one. Again, think about what’s going on, how many duties are being processed each stroke, and consider those processes, and it’s clear that this big bad boy best be fastened down. It’s noticeably easier to operate a progressive when it’s mounted rigidly. Some progressives seat the primer on the press handle upstroke, some on the downstroke (most are on the upstroke). A rigidly-mounted press adds to the feel of this operation.

Get “good” dies. Most progressives, and certainly the popular machines, can accommodate any 7/8-14 threaded die. Feel free, and encouraged, to use the “better” sizing and seating dies, just as you might for a single-stage press.

Incorporate a good quality powder meter (something with a 7/8-14 attachment means). This can be done via a “conversion kit,” if the machine isn’t already outfitted with linkage that will cycle the powder meter operating handle. Makes a huge difference here, just as it does regardless of press type.

Address primer pockets. The priming operation inherent in a progressive doesn’t provide the feel of a bench-mounted or hand-operated tool. That’s not a problem at all if the primers are being seated fully using a progressive. To help ensure that they do, I think it’s wise to run a pocket uniformer. That way, the pocket will be what it should be, so the priming operation should likewise result in a well-seated primer. At the least, check each and every loaded round you get of a progressive for a high primer. Sometimes the machine needs to be adjusted, by the way, to seat primers fully.

Caveats? There are a few, not many.

I have long and often said that the big reason I don’t use a progressive for all my ammunition is because I really never get to see one run. By that I mean the increased ease and speed potential of a progressive is wasted on me because of my loading habits. It all stops, dead in its tracks, with case preparation steps, which includes the steps themselves and maybe even more the order in which I do them. Once I get my case prep work done, actually loading each round comes down to dispensing a propellant charge, putting a bullet into the case mouth, and running it up into a bullet seating die. I can do that rapidly. However! And here’s the hold up, before I get a cartridge case to that point, I have to do all the sizing operations on it. A bigger-scale progressive would give me the means to size each case fully, which is body, neck, and then neck inside, so there’s an extra operation (the inside neck sizing). Again, if there’s a threaded hole for a die and a station point underneath that, it could work for me. But if I have to do the sizing and then, say, trimming, everything breaks down, and slows down.

I’ve been most wrongfully accused of knocking progressives. Not even a little bit am I doing that. The closer your starting point (sizing a clean case) is to your ending point (seating a bullet) the better a progressive will reward you. That’s all’s I’m saying.

Hornady Progressive Press
Progressive reloading presses are not at all just for straight-wall pistol cases. High-quality, precisely-constructed ammo can be produced on a progressive. Just need the right tooling and the right approaches. A “big” progressive, like this Hornady, can handle virtually any cartridge.

You will find, and it will be a natural evolution of your approach, that there is larger volume preparation work done for progressives. All I intend to suggest in that is that, as round-count volume increases, so too will round-count preparation. When I use a progressive I tend to “save up” empties and run bigger batches. Ways you might find to improve handling larger quantities is to split up bench sessions for decapping, cleaning, trimming, applying lube (even though I don’t think they work all that well, the spray-on lubes work easiest for prepping large quantities of cases), or whatever else you do prior to announcing a case is fit for a reload. I really think you should decap cases prior to running them on a progressive. Keep the press as clean as you can. Primer grit residue doesn’t help. Pay special attention to the keeping the priming station area clean.

decapping die
I strongly recommend using a decapping die prior to placing the cases on the shellplate. There’s a lot of grit otherwise that’s getting onto the mechanism. Pay particular attention to progressive priming parts: be watchful for any debris that could conceivably detonate a primer; that could be catastrophic.

The preceding was adapted from Glen Zediker’s newest book, Top-Grade Ammo, now available! Visit ZedkerPublishing.com or BuyZedikerBooks.com for more information. 

Improving Tool Alignment: 5 Ways To “Float”

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“If it’s not perfectly aligned, then it should float…” Here’s a few tips on improving concentricity in the handloading process.


Glen Zediker


Water seeks its own level. Moving parts seek their own centers. Trick is getting the centers to agree. When centers coincide, that’s “concentricity,” and that a prime goal in the process of creating better ammunition. Anything under pressure and moveable, such as a cartridge case being sized or a bullet being seated into a case neck, moves toward a path of least resistance. If all the tooling associated is straight, and the case hisseff is uniform, then the result is “straight.” However! That’s in a perfect world.

In reality, which is accepting existence of tolerances and misalignments, taking steps to help two conflicting centers come close together comes from providing some free-play in the apparatus. I call it “floating.” And it works, and here are a few ways to use it.

Now, free-floating can work two ways. One is to incorporate a float into the mechanism in use, and another is to create float, and then use that to center a piece prior to snugging it down.

1. Shellholder
This first one might seem a tad amount clumsy, but it’s really easy to get used to in operation. Presses with conventional shellholder arrangements use a spring clip to retain the shellholder in its slot atop the press ram. Get this clip gone! It cocks the shellholder askew.

The solution is to incorporate an o-ring to retain the shellholder in its slot. Get one at any real hardware store. Size that works is usually 7/8-inch outside diameter, 11/16 inside diameter, 3/32 thickness. The o-ring fits into the exterior channel previously occupied by the spring clip. To install a shellholder you just roll the ring down a tad, slide in the holder, and let the ring back up to block its exit out the front.

This modification lets the shellholder sit flat, as it should, and also provides some wiggle room so the case can align itself with the die opening. [Photo from Top-Grade Ammo]
This modification lets the shellholder sit flat, as it should, and also provides some wiggle room so the case can align itself with the die opening. [Photo from Top-Grade Ammo]
2. Sizing die lock ring
Speaking of wiggle room, there’s a whopping lot of it in a 7/8-14 thread set. That’s pretty coarse. Taking up the play created by thread-to-thread gaps goes a good ways toward “straight” installation of a die into a press. There are a couple of ways to help this.

One is to always (always) tighten a die locking collar ring when there is a case inside the die, and the ram is fully extended upward (handle all the way down). This bit of pressure helps to bring the die into straight alignment. Problem is that it also makes the daggone die hard to remove. Just get stern with it. After initial removal, subsequent re-fittings are easy. I use a “strap wrench” (plumbing supply and real auto parts stores have one for you) if it’s stubborn to turn loose after being tightened initally. Pliers result in cosmetic, but not real, damage. Lock rings with wrench-flats are dandy.

Always put an index mark from die lock ring to die body to press top. That’s a simple way to verify return to “zero” when a die is installed back into your press. And ALWAYS install and remove the die holding ONLY the locking ring! Never-ever the die body. Any teeny body rotation within the locking ring, which is easily undetectable, requires repeating the process of die adjustment.
Always put an index mark from die lock ring to die body to press top. That’s a simple way to verify return to “zero” when a die is installed back into your press. And ALWAYS install and remove the die holding ONLY the locking ring! Never-ever the die body. Any teeny body rotation within the locking ring, which is easily undetectable, requires repeating the process of die adjustment.
I prefer clamping lock rings, like these from Forster. Those with a set screw can cock when the screw tightens in against the angled threads.
I prefer clamping lock rings, like these from Forster. Those with a set screw can cock when the screw tightens in against the angled threads.

For these tricks, choose a case that represents your best: get one with the most consistent neck wall thickness.


3. Expander/decapping assembly
There’s some “feel” involved in this one, but it is worthwhile. To get the expander in your sizing die sitting on center, run up a case fully and then slowly withdraw it until you feel the expander lodge inside the case neck. Then put a little pressure down on the handle, in the direction of raising the ram, while you tighten the locking apparatus.

When it’s possible, and it almost always is, secure the pieces-parts when they’re doing their jobs. For instance, tightening the locking rings on a decapping stem when the expander is holding inside the case neck helps bring the stem into straight alignment, and the expander along with it.
When it’s possible, and it almost always is, secure the pieces-parts when they’re doing their jobs. For instance, tightening the locking rings on a decapping stem when the expander is holding inside the case neck helps bring the stem into straight alignment, and the expander along with it.

4. Lock-ring o-rings
Here’s one I suggest but don’t usually follow… Lemmesplain: It works but I prefer these other means because they’re more “secure.” However! Installing an o-ring up under the die body locking ring (sizers and seaters) provides a cushioned flexibility that provides for takeup in the amount and “direction” needed when a case is run up into a die. O-ring size is 7/8-inch inside diameter and a thickness of 1/8-inch.

O-ring trick: the flexible ring allows for some “wiggle room” to help case and die centers match. Trick is reinstalling the die to hold the desired setting, and the index mark really helps. Hold only the lock ring when threading the die in and out!!
O-ring trick: the flexible ring allows for some “wiggle room” to help case and die centers match. Trick is reinstalling the die to hold the desired setting, and the index mark really helps. Hold only the lock ring when threading the die in and out!!

5. Bullet seating die stem
This one is pretty simple: tighten the lock on the stem when there’s a seated bullet run up into the die. Threads are finer on stems than on die bodies, but better is a better. This is for a conventional-style seating arrangement. Those that use a spring-loaded sleeve arrangement, like a Redding Competition Seater, are good to go as are.


The preceding is a specially-adapted excerpt from the book Top-Grade Ammo just released by Zediker Publishing.

Load Testing Insight: 5 “Rules” for Load Work-Up

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Don’t waste time and money collecting half-boxes of “loser loads.” Here’s how to start and finish load work-up in one day.


Glen Zediker


Last time I talked a little about keeping your ammo pressure-safe, under a range of conditions. Quite a bit of that dealt with observations made during load work-up. So this time I’d like to talk more about the work-up process I use.

The reason for the term “work-up a load” is pretty clear: we’re almost always looking to get the highest velocity we can, safely. High velocity, or, more clear, higher velocity, is usually all good. Shorter time of bullet flight to the target means less drop and drift, and a harder impact.

So working up means increasing propellant charge incrementally until we’re happy. Happy with the velocity or happy that the cases are still able to hold water. Ha. As said last time, it’s vitally and critically important to have a stopping place, a goal to be reached, prior to testing.

I also mentioned an “incremental” load work-up method that I have followed for many years, and it’s served me very well. I do all my testing and work-ups at the range. I load right then and there. I take boxes of sized and primed cases, and my Harrell’s powder meter, and a small press that I c-clamp to a bench. The press, of course contains my seating die. And the most important pieces of gear are a notebook and a chronograph.

load at the range
You don’t have to invest a fortune to take your handloading show on the road. Some c-clamps and one of these little Lee Reloader presses is all you need! And a good powder meter. One with a clamp is handiest, or just mount it to a piece of wood and clamp that down (even a pickup tailgate works just fine).

Before the trip, I have taken the preparation time, done the homework, to know exactly how much “one click” is worth on my meter. It varies with the propellant, but by weighing several examples of each click-stop variation (done over at least 4 stops) I can accurately increase the charge for each test a known amount.

reloading at the range
I map out the incremental values of each click on my Harrell’s meter adjustment drum with the propellant I’ll be testing, and it’s really easy to step up each trial with confidence. I carry the whole kit in a large tackle-type box.

I work up 0.20 grains at a time. Sometimes it’s more if I’m reading a low velocity initially. Since I have a meter with a “Culver” insert, which I trust completely, I actually reference the number of clicks in my notes rather than the weights. I check after the weights when I get back home, and I do that by counting to the setting and weighing the charge. It’s easy enough also to throw a charge into a case and seal it over with masking tape.

I started loading at the range because I got tired of bringing home partial batches of loser loads. And, you guessed it, the partial boxes usually contained recipes that were too hot. The only way to salvage those is to pull the bullets. Tedious. Or they were too low, of course, and fit only for busting up dirt clods. Plus, I’m able to test different charges in the same conditions. It’s a small investment that’s a huge time-saver.

During my work-up, I fire 3 rounds per increment. As it gets closer to done, I increase that to 5. Final testing is done with 1 20-round group. Does 3-round volleys seem inadequate? It’s not if there’s confidence that the rounds are being well-directed and speed is being monitored. If I’m seeing more than 10-12 fps velocity spreads over 3 rounds, I’m not going to continue with that propellant.

Here are a few things I’ve found over the years to better ensure reliable results. Learned, of course, the hard way.

  1. Limit testing to no more than one variable. I test one propellant at a time, per trip. If you want to test more than one on one day, bring the bore cleaning kit and use it between propellant changes. Results are corrupt if you’re “mixing” residues. Same goes for bullets. Otherwise, though, don’t clean the barrel during the test. Don’t know about you, but I fire my most important rounds after 60+ rounds have gone through it, so I want a realistic evaluation of accuracy (and zero).
  1. Replace the cases back into the container in the order they were fired. This allows for accurate post-testing measurements. Use masking tape and staggered rows to identify the steps. I use 100-round ammo boxes because they have enough room to delineate the progress.

    ammo pressure
    Keep track of the cases in the order they were fired. This helps later on back in the shop when the effects can be measured. This little outing here, though, didn’t require a gage to cipher: a tad amount hot on that last little go around (last case bottom row on the right). Thing is, I didn’t load a whole boxful of those chamber bombs to take with me, and that’s the beauty of loading right at the range.
  1. Use the same target for the entire session. (Put pasters over the previous holes if you want, but don’t change paper.) This helps determine vertical consistency as you work up (when you’ve found a propellant that shows consistency over a 3-4 increment range, that’s better than good).
  1. Exploit potentials. If you take the lead to assemble a “portable” loading kit, the possibilities for other tests are wide open. Try some seating depth experiments, for instance. Such requires the use of a “micrometer” style die that has indexable and incremental settings.
  1. Go up 0.20 grains but come off 0.50 grains! Said last time but important enough to say again here. If a load EVER shows a pressure sign, even just one round, come off 0.50 grains, not 0.10 or 0.20. Believe me on this one…

Last: Keep the propellant out of the sun! I transport it in a cooler.

shooting chrony
Chronograph each round you fire. It doesn’t have to cost a fortune to get an accurate chronograph. This one is inexpensive and, my tests shooting over it and my very expensive “other” brand chronograph (literally one cradled in the other) showed zero difference in accuracy. The more expensive chronographs mostly offer more functions. The muzzle-mounted chronos are fine and dandy too.

The preceding was a specially adapted excerpt from the new book, Top-Grade Ammo by Glen Zediker. Check it out at ZedikerPublishing.com or BuyZedikerBooks.com

5 Steps to “Pressure-Proofing” Handloads

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Here’s a few ideas on how to proceed in load testing to find the safe maximum velocity, and keep it safe…

We’ve chosen the sometimes twisting path to becoming handloaders because we want to improve on-target results. The difference between a handloader and a reloader? My wise-crack answer, which is honest, is that handloaders start off with new brass… We’re not about to shoot factory ammo.

Part of the process of developing the load we’re seeking is learning how to safely set a cap on its pressure. Most of us don’t have pressure-testing equipment, so we rely on measurements and observation to know when we’re at the limit. The goal often, all other things being the same, is to find the highest velocity we can get. Less drift and drop, shorter time of flight, all good. However! Knowing that the maximum tested velocity is also going to be safe over the long haul is a much narrower line to walk.

There’s not room here to cover every pressure check, all the symptoms that can point out over-pressure ammo, but I’ll share my two leading indicators: primer pockets and velocities.

  1. Always start load development with new brass! There are a few reasons, but the leading one related to this material is that the primer pockets will be at their smallest. So. Fire the cases, size the cases, and seat new primers. It takes a little experience, which means a few times through this process, but my leading indicator of pressure is how easily the primers seat. They’ll go in easier than on the first use, but if there is much less to very little resistance felt the second time around, that load is over-pressure. Period. The case head has expanded (I put a max of 0.0005 on expansion, when it’s measured with a micrometer). The more you use the same cases and repeat this process, the sooner you’ll get a handle on the feel to know when the primer pocket has overly expanded.
seating primer to check pressure
My primary gauge for pressure is primer seating — how easily a new primer seats into a once-fired case. This is an indication of case head expansion. It won’t be as tight as new, but it should still be snug. A low-leverage tool, like this Forster Co-Ax, increases the feel and feedback of this operation.
  1. Jump back, don’t step back. If you encounter a pressure symptom, come off a “whole” half-grain. Not a tenth or two. And if you see it again, come off another half-grain. Folks, if anyone thinks the difference between over-pressure and safe-pressure is 0.10-grain, that same little bit exists in the difference in 20-degrees ambient temperature with many propellants. Don’t cut it that close. Keep the long-haul in mind.
  1. Select a temperature-insensitive propellant (related to the above). There will be one out there you’ll like. I use a single-base extruded (stick) propellant when loading for the season. The propellants I choose are coated to help reduce temperature-induced changes. That season is going to span a 50+-degree range, and I don’t want August (or October) to force me back to the loading room… Temperature sensitivity works “both” ways, by the way… Hot or cold can induce pressure increases.
  1. Read the speed on each and every round tested. Beforehand, I have to assume you’ve gotten an idea in mind of what you’re looking to get for a muzzle velocity. If not, do that… A journey of this nature has to have a destination. If not you won’t know when you get there. If you are reading velocities more than 40-50 feet per second over a published maximum, that’s a flag. That 40-50 fps is usually about a half-grain of most propellants in most small- to medium-capacity cases. Certainly, there are all manner of reasons some combinations can vary, but, despite what your mother might have told you, you are really not THAT special…
  1. Don’t assume anything. If you have one round out of many that “suddenly” exhibits pressure symptoms, don’t guess that it’s just a fluke. It’s not a fluke. You finally saw it. Overwhelming chances are that the load is over-pressure and has been over pressure, and the question is how much for how long? Back it off. (The way you know it might have been a fluke, and that happens, is again based on how close to a velocity ceiling it is: if it’s a real mid-range velocity load, it might have been a fluke.)
primer indicators for over-pressure ammo
Some over-pressure indications are pretty clear. Left to right: new, nice and safe (notice there’s still a radius on the primer edge), cratered and flat, yikes! It’s another article, but not all piercings are caused solely by high-pressure ammo; an overly large firing pin hole size in an AR15 bolt contributes.

One last about primer appearances. Usually the first thing a handloader will do after firing a round is look at the primer. I do. No doubt, if the primer is flattened, cratered, pitted, or pierced that’s a honking red flag, and the immediate response is, you guessed it, come off a “whole” half-grain. However. Small rifle primers (especially some primers in some cartridges) do not exhibit the common over-pressure appearances. They can look just fine and shiny until they blow slap out. If you ever see anything that looks like a pressure symptom, back it off; however, don’t assume a load can’t be running hot if the primers don’t show it.

over pressure ammo, primer appearance
Here’s what I mean about primer surface indications not always revealing high pressure. The middle one is an incredibly over-pressure load fired through one of my AR15 race-guns with an extra-heavy bolt carrier. Primer looks just fine. Right hand case is what happened without the extra weight. Neither case would hold a primer after this one firing.

Back to the start: primer seating and velocity are the leading indicators.


The preceding contains specially-adapted excerpts from the new book “Top-Grade Ammo” by Glen Zediker and Zediker Publishing. See it by visiting ZedikerPublishing.com.

Throat Erosion, Part II

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The following is a specially-adapted excerpt from the forthcoming book “Top Grade Ammo” by Zediker Publishing. BuyZedikerBooks.com for more.

by Glen Zediker

We talked about rifle barrel throat erosion last time, in descriptive terms. Short course: It’s the area just ahead of the case neck area in a rifle chamber that bears the majority of the “flame cutting” effect of burning propellant gases. The wear in this area determines the accurate life of a barrel. The greatest detractor from accuracy is the roughness that results from the deteriorating steel surface. Of course, the throat is advancing, getting longer, at the same time. After time, the “jump” or gap the bullet has to leap before engaging the lands plays its part in poor on-target performance.

I’ve always followed a “scheduled” replacement plan on barrels, determined, of course, after much experimentation and many measurements. That’s for competition rifles. For others, I have a more-or-less “shoot it until it doesn’t shoot well” approach.

If you chronograph frequently enough, and are using the same load, you’ll see velocities drop as more rounds go through the barrel. This is because of the lengthening throat: more room for expanding gases, lower pressure, lower velocity. I know a few who gauge barrel replacements based around chronograph readings, and the resultant propellant charge adjustment necessary to maintain “new barrel” bullet speed. The general consensus, for a round with approximately .308 Win. case capacity, is 2.0gr. So when it takes another 2 grains of propellant to restore original velocity, that one’s done.

Here are a few more ideas on barrel life, and also a few thoughts on how to keep a barrel shooting better longer.

Last time I made a statement that I should have qualified more, but space is always such a concern in these articles. It was respecting the idea of pulling a barrel, cutting some off its chamber-end, and then rechambering it. This overwrites the eroded area, well most of it. That can only be done for a bolt-action rifle. I said that worked well for chromemoly barrels but not for stainless steel barrels, and the difference is in the “machine-ability” of the steels. It is possible to set back a stainless barrel, but it’s tough to have a

“chatterless” cut result. A little more usually needs to be removed to get good results with stainless, and this, of course, is making the barrel overall that much shorter. Certainly: you have to plan on a set-back at original barrel installation, and that means include enough extra length to compromise. Usually it takes a minimum of 1 inch to get a worthwhile result with chromemoly.

So what can reduce the effects or severity of erosion, which is only to say prolong the life of the barrel? Reasonable does of propellant behind lighter-weight bullets, that’s one. Another is that flat-base bullets do result in less cutting than boat-tails. Flat-base bullets “obturate” more quickly. Obturate means to “block,” but here it means to close a hole, which is a barrel bore, which means to seal it. The angled tail on a conventional boat-tails creates a sort of “nozzle” effect, directing gases to the steel surface. Can’t much be done about that, though, because when we need boat-tails we need them. However! A relatively obscure but well-proven boat-tail design does increase barrel life, and also tends to shoot better though a worn throat. A “rebated” boat-tail has a 90-degree step down from the bullet shank (body) to the tail. It steps down before the boat-tail taper is formed. These obturate fully and quickly. It is common for competitive .308 shooters to switch from the popular Sierra 190gr MatchKing to a Lapua 185 rebated boat-tail when accuracy starts to fall off due to throat wear. Sure enough, the Lapua brings it back for a couple hundred more rounds.

Some propellants burn lower temperatures than others. Some double-based propellants claim this, and, true, if you can be happy with the performance of one, it can extend barrel life a few hundred extra rounds. WW 748 is one of those propellants and my experience with it is that the claims are true. It’s not night-and-day, but there’s a difference. Research to find others.

Coated bullets don’t have any influence on throat erosion, but they tend to perform better though a rough throat. Boron-nitride is the only bullet coating I can recommend. I use it. Do an extra-good job cleaning the throat area in a wearing barrel. Copper and other residues tend to collect more as the steel gets rougher and rougher.