RELOADERS CORNER: 4 Firings In, Part Two

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Cartridge cases always fail on the “next firing.” Question is which one that might be. Need to know! KEEP READING

beat case
I apologize for the image quality, but these were taken a while ago. Fortunately, for me, I didn’t have anything on hand that shows even close to the beating this one took. Cracked neck, head crack. Rare to see one case with both of the most common failures. It was attacked by an M14.

Glen Zediker

I’d always rather say it all at once, but the realities of tolerance, and space, sometimes mean I have to split a bigger topic into smaller installments. The “tolerance” part is how many pages you all are willing to scroll through!

This multi-part topic is when, and then how, to check after the progress of changes commencing with the firing on a new case. It’s the “progress of degeneration,” in a way of looking at it because the concern is getting a handle on when enough change in the brass has come about to require attention. Or abandonment. As said then, for me that’s 4 firings. That, as said last time, is when I might see changes that need attention. Also as said, that figure didn’t come out of a hat, but from my own notes in running my competition NRA High Power Rifle loads.

The areas most affected are the case neck and case head area. Case neck walls get thicker, and that was the focus last time. Well, the case head area body walls get thinner. Primer pockets get shallower and larger diameter.

As started on: Brass flows during firing. It expands, then contracts, and when we resize the case, it contracts, then expands (a little). This expansion and contraction makes the alloy harder over the entire case, but with more effect in areas of more expansion, and flow. Replace “hard” with its effect, “brittle,” and that’s a clearer picture. This increasing hardness influences its reaction to being sized or otherwise stretched. As with many metals, bend it back and forth enough times and it will break. It will also fail if it loses enough resilience, or thickness, to withstand the pressures of firing.

Case Head
When a case is under pressure during firing, the brass, like water, flows where it can, where it’s more free to move. Of course, the chamber steel limits the amount it can expand. The case shoulder blows fully forward and the case base is slammed back against the bolt face. There is, therefore and in effect, a tug on both ends — it gets stretched. The shoulder area is relatively free to expand to conform to the chamber, but the other end, the case head area, is not. Since that’s the area of the case with the thickest walls, it doesn’t expand “out” much at all. What it does is stretch.

The “case head area,” as I refer to it here, is the portion of the case above the web, which is just above the taper that leads in to the extractor groove. The “area” extends approximately an eighth-inch up the case body.

case pressure ring
Here’s a “pressure ring.” You’ll see this after firing, if you see it. And, if you see it, that case is done. The bright ring indicates excessive stretching, which indicates excessive thinning.
head separation pic
Closer view of another sectioned case. This one here was fixin to pop. 

That portion of the case does not fully expand and grip the chamber, but the area immediately ahead of it does. So the case body expands and grips the chamber, and that last little bit back to the base can and does move. It stretches. If you see a ring circling the case, noticeable because it’s lighter color than the case body, and it’s in this area, I’d say that case is done. The ring will be evident after firing, not after; don’t confuse a shiny ring around the case in this area with what can be normal from sizing, especially if it’s been a hotter load. That is pretty much a scuff from the sizing die squeezing down this expanded area.

And that’s right where a “head separation” occurs. It can crack and also blow slap in two, and that’s the “separation” part of case head separation.

This is a spot to keep close watch on as cases age. It is also the area that is more “protected” by sizing with less case shoulder set-back. That is, pretty much, where the freedom for the stretching movement in this area comes from (the case shoulder creates a gap). However! As said many a time, semi-autos need some shoulder set back for function, and it’s the reason to use an accurate gage to determine the amount of set-back needed.

case head separation
Ultra-high-precision gage, made by me. Not really. It’s a selectively bent paper clip, and running this down inside the case and and then back up the case wall can signal a dip-in in the head area, which signals thinned walls. Feel it? Case is done.

Some folks unbend a paper clip and run it down inside a case and drag it up against the inside case wall as a sort of antenna to see if they detect a dip-in near the head area, which would indicate that the wall in this area has been stretched thinner. If there’s enough to feel it, that case is done.

Since I’m working off this “4 Firings In” checklist, if you’re seeing a sign that a head separation might be nigh in that few uses, chances are the shoulder set-back is excessive, and also too may be the load pressure level.

Primer Pocket
Another case-head-area and pressure-related check is the primer pocket. As said, the primer pocket will get larger in diameter and shallower in depth each firing. As with many such things, the questions are “when” and “how much,” and the main thing, “how much?”

If the pocket gets excessively shallow, and that’s judged by a primer that seats fully but isn’t at least a tick below flush with the case base, there could be function issues. There’s a risk of a “slam-fire” with a semi-auto that uses a floating firing pin, and, if there is actual protrusion, that has the same effect as insufficient headspace.

primer pocket uniformer
A primer pocket uniformer can reset the depth of a shallowed primer pocket to what it should be, but the real test for me is how easily the next primer seats into it. If it’s significantly less resistance, I’ll say that case is done.

Shallower can be refurbished. That’s a primary function of a primer pocket uniformer. Larger diameter, though, can’t be fixed. I’ve mentioned in another article or two that, any more at least, my main gauge of load pressure has become how much primer pocket expansion there’s been. I judge that without using the first gage, well, unless my primer seater is a gage. If a primer seats noticeably easier, that’s the clear clue that the pocket is too big. Another is seeing a dark ring around a fired primer, indicating a little gas leakage.

Measuring primer pockets is a waste of time, say my notes at least. First, it’s not easy to accurately (truly accurately) measure a pocket, especially its diameter, but, that’s not really what matters. It’s how much grip there is to maintain the primer in place during firing.

I pay close attention to resistance in primer seating and won’t reuse a case that’s too easy.

Good deal on what I think is good brass, especially if you’re an AR15 loader — HERE

Glen’s books, Handloading For Competition and Top-Grade Ammo, are available at Midsouth HERE. For more information about other books by Glen, visit ZedikerPublishing.com

Glen’s newest book, America’s Gun: The Practical AR15. Check it out HERE

par15

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14 thoughts on “RELOADERS CORNER: 4 Firings In, Part Two”

  1. I reload 7mm. Remington Mag cartridges. And I want to use them exclusively in my Savage 111 bolt Rifle.
    They are more accurate than commercial ammo and much cheaper plus fun to do. I use Winchester primers, IMR4350 powder, and 139 grain bullets ( and 150 grain Nosler ballistic tips too ) and Hornady reloaded and dies.
    I weigh each case and group them into twenty cases that are within 1 grain of each other. My powder is within 0.1 grains using a trickle charger and all cases are identical when trimmed to Overall case length. I even clean the primer pockets everytime.
    My question is how much more accurate can it be to only resize the neck and how often would/should the case need to be full resized. And how long can a case last compared to full resizing each time?
    Is it “worth” annealing the neck at home also?
    Thanks for anyone’s suggestions.

    1. I suggest you purchase the Hornady Head Space and Over-All Length Comparators.
      1. trim all brass to minimum over-all length
      1. measure unfired, un-sized case for “baseline” (using head space gauge
      2. load and fire shells as per your process. I would suggest seating the projectiles .020 inches off of the lands of the bore. This dimension can be determined very easily using the Hornady OAL Length Comparator and “Modified” shell. This tool measures the distance from the case head to the ogive of the projectile and not the meplat.
      3. fire the loads
      4. measure cases again with headspace gauge. and record
      5. When resizing, the shoulder should not be pushed back more than .001 or .002 inches to prevent over working your cartridges. The advantage will be obtaining an optimally accurate “custom” fit shell that will reliably function in your firearm while maximizing case life and accuracy.
      Incidentally, I have the same rifle in the same chambering and am working on the Sierra 165 grain Tipped Game King with H1000.

  2. if you are reloading brass that was fired in your bolt action or single shot rifle and it has a concentric chamber there is no need to ever do a full resize. you may get an extra 3 -4 reloads per case. if you have any problem getting the bolt to close with the neck sized brass you may have to bump the shoulder. belted mags used to headspace on the belts, that is not always the case today as the belts are for visual effects and serve no real purpose as the rifle still headspaces on the shoulder of the cartridge.
    now the disclaimer. if your rifle has a bad chamber,out of round/egg shaped do to a poor polish job ect you will still need to full resize to get the cartridges to feed. in a semi auto/auto you need to full size every time you reload the brass.
    since you are talking about the 7 mag you will probably have a problem with the primer pocket enlarging before the case neck becomes brittle or cracks.
    my 300 wby often has 0 reloads after firing factory loaded ammo from several manufacturers because the primer pockets stretch to the point they wont hold the new primer.
    as for neck sized brass being more accurate than full size, i have not found that to be true in the 30+ years i have been reloading.

    1. Agreed, I neck size only after first firing. I shoot .308 and get on average 8 uses per case

  3. I get along with brass and can not count the loads from rifles. But I shoot and hunt with revolvers most and I am still using brass from about 1979 when I started IHMSA, hash marks on one MTM box show 45 loadings. I neck size for the .44 SBH and it creates a dilemma since those cases will not enter the SRH so I keep them separate.
    I lost count of primers used in the SBH but it as well over 93,000 rounds with no wear I can measure. Just some sandblasting at the cone edges.
    I next found Hornady dies make the most accurate loads and equal my BR dies. I have had dies that size the neck too much and the expander will bend the shoulders to make run out bad. I lap the die for minimum sizing of the neck.
    The collar dies from Redding work great too but after so many shots cases get tight so a FL will be needed now and then. Same with a Lee collet die, works fine but you also need a FL die. There is no difference in accuracy between neck and FL sizing. Never set shoulders back and keep run out under .002″ if you need to outside neck turn to even thickness only.
    Brass is evil for sure so you just need to learn it. Have fun my friends.

  4. The bent paperclip tool works great for me on the smaller caliber rifle cases but on .45 caliber and larger I use an LED powered flashlight and look inside for a shadow line indicating head wall thinning. It is much faster for me than the paperclip method.

  5. Due to lack of time, my loading requirements for 308 and 223 have gravitated toward using ” once fired” processed cases, ready for priming and loading. FYI and that of your followers, the quality varies from supplier to supplier. Over the last couple years I have encountered faulty headspacing, cracked cases leading to separations, and primer pockets insufficiently reamed. One 500 pc bag had to have primer pockets reamed by me, and another bag would not fit in M1A

  6. Ballistic Tools makes a primer pocket, go, no-go gauge. It was designed for swage primer pockets but can be used to test a primer pocket for size and depth. You can get a three gauge set, small, large primer, and neck tension gauge for 224, 308, and 311. for $30.00 plus shipping. So there’s no need to try and measure the gauge will tell you if the primer pocket need attention or the case needs to in the brass bucket for recycling.
    This is not a add by the manufacturer just thought others would like to know that there are helpful tools out there if you just know where to look.

  7. I keep reading about the necessity of full length resizing for semi-autos, but I just haven’t found that to be true on several semi-autos that I own and have reloaded for since 1970. For years, I used a Lee loader set, the one that only neck sizes and you do everything with a small mallet or brass hammer. .223 REM for a Costa Mesa manufactured AR-180. Never had a failure to feed, chamber, eject, or anything else. The same for an M1A beginning about 1996. Same type of Lee kit, .308 WIN. Never had a single problem. I’m getting older now, and the wife bought me a regular RCBS press in 2016 (said she was tired of all the hammering). I full length resize for those guns now, but the little Lee kit and my brass hammer are still stored in the closet and I’ll use them again if I need to reload in the field for some reason. So, depending on the gun, I would have to say that you MIGHT need to full length re-size for a semi-auto, but more than 40 years of experience with my semi-autos says that full length re-sizing is optional. And the brass gets lost before the necks harden enough to develop cracks. With full length re-sizing I need to anneal the necks every 3 or 4 times through the press.

    1. If it chambers it is good to go but I had a Rem 760 in .270 that would not chamber unless FL sized. There is just no force with a pump gun to close the action. I never had to go to the SB size die.
      I never anneal unless forming cases since it is too hard to make all the same tension. Case tension is a very important thing and keeping every case the same is too hard.

  8. I have found a primer that fits a little looser does no harm but you do not want any leakage. With the proper head space the primer backs out and the expanding brass will re-seat it. The primer cup will also expand to seal.
    Long ago Federal had some primers that corroded and leaked at the edges. They would cut a ring on the bolt face. It was traced to the cup cleaning solution and there was a recall.
    Another thing to think about is neck tension in a rifle as well as revolvers, it must be enough and even. You should use the entire neck length when you seat a bullet and never try to reach rifling on a rifle with a long throat. What happens is the primer will push the bullet out early to become a bore obstruction before the powder is fully ignited— the S.E.E. occurrence. It is never the same but it will expand the base, primer pocket and expansion ring. You can even fire many shots until one gives way. Bullet jump to the rifling has never proven to harm accuracy. Same thing will happen with some powders reduced that will become a plug to push out a bullet because of airspace.
    Brass is not all the same, A-Max brass can not be loaded again and S&B can fail the second shot. I have a bag full of S&B case heads a friend loaded. He carries a rod and brush to my range to remove the rest of the case.
    Loading is easy but knowing everything takes years and years but to me safety for myself and everyone is the most important. If primer pockets are expanding in a few shots you are doing something very, very wrong.

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