Tag Archives: advanced handloading

RELOADERS CORNER: Crimp

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More “factory tricks” can be applied to handloads, if you feel a need. READ MORE

crimp
To get a sano crimp, the bullet has to have a crimping groove, or cannelure, for the case mouth to roll into, and the die itself has to be internally dimensioned to accommodate it.

Glen Zediker

A commonly used tactic in a factory round is a crimp to help hold the bullet in place before it’s launched, especially when there is a heavy bullet and heavy recoil. Inertia generated within the gun, in a big part, can make the bullet shift, usually outward (common in a magnum revolver). A crimp also helps guard against a bullet seating more deeply, as when there might some stubbing contact as the round is chambered.

For a true factory style roll crimp, the bullets must have a cannelure, or “crimping groove.” This is a ring cut into a portion of the bullet’s major diameter. The edge of the case mouth is turned or folded (“rolled”) into this groove to complete the crimp. The bullet seating die has to be tooled to provide this effect when it’s adjusted properly to engage the crimping groove. Not all seating dies can provide crimp.

If your die allows it, to get a crimp, adjust bullet seating depth to put the cannelure so it’s right on the end of the case mouth. Then adjust the die body downward to engage the crimping ledge so it will pinch the edge of the case mouth into the groove.

crimp
Here’s a good example of a good application of crimp. This 300 Blackout subsonic has a heavy bullet that otherwise can be prone to shift as a result of intertia induced forces at work during action cycling.

I don’t usually use a factory style roll crimp because I’ve never felt need for it, and also I convinced myself that it can’t be a good idea (ever) to squeeze in on a bullet, or not when best group size is the goal. Another reason is that I very rarely use a bullet that has a cannelure. However! I concede those times when it is a benefit. I crimp magnum handgun loads.

Also, if you crimp, it’s clear there are strict and unweilding limitations on bullet seating depth and also that all the cases have to be the same height for it to work properly, and that means at least a little additional tedium from efforts in case trimming.

crimp
Lee has a really good setup, in my experience and opinion, for those who want to closely duplicate factory treatment. It’s their “Factory Crimp” die.

An alternative to a roll crimp is a “taper crimp.” This is popular with practical-style pistol competitors and also with a couple of commercial .223 Rem. loaders I know. A taper crimp die does what it suggests or sounds like it does: it squeezes in some portion below the case mouth against the bullet using a gentle taper. Anyone who’s loaded straight-walled cases knows about “belling” the case mouth. Belling makes a little funnel-edge on the case mouth to allow easy entry for a bullet. That tiny trumpet-shaped area then needs to be ironed back flat so the round will chamber, and the seating die has a portion within it dimensioned and devoted to this chore. A taper crimp die works in the same, just more.

crimp
Here’s a taper crimp die. These give a progressive and relatively gentle squeeze down that adds a little more grip againt the case neck. It’s also an asset to feeding for a semi-auto.

And, as said, a taper crimp is a stand-alone die, which means it’s best used in a turret or progressive style press. Its use effectively increases the grip against the bullet. Some say it’s an asset to reliable feeding, and I can agree with that given straight-wall cases, but I don’t think it helps a bottleneck case in this regard. It will, however, keep the bullet better in place against outside forces seeking to change its location.

crimp
A healthy crimp is common also in hard kicking heavy bullet rounds like magnums. The idea here is to keep the other bullets in place in reaction to the firing forces trying to dislodge them.

Last, for now, is that there are also a good many who claim that crimping is an asset to improving round to round velocity consistency. Judge that, along of course with your chronograph, but I have yet to see it in rifle ammunition. Some pistol ammo, yes.

Check out Midsouth taper crimp dies HERE

Lee “Factory Crimp” HERE

The preceding is a adapted from information contained in from Glen’s newest book America’s Gun: The Practical AR15. Available at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.

RELOADERS CORNER: Factory Tricks

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A few factory “tricks” can be applied to handloads, if you feel a need. READ MORE

ammo storage
Handling precautions during round assembly and then good storage afterward extends the shelf life of reloads.

Glen Zediker

Last time we took a look at some of the differences between factory-loaded ammo and our own recipe handloads. That material wasn’t a total indictment on factory ammo as might have been expected coming from me and directed toward mine, and that’s because there are some times ready-made has its place.

One of the main-most good things that can be said about factory ammo is that it has a shelf life that, given decent storage conditions, will likely exceed that of handloads. Or not. “Not” depends on what steps or processes were applied to the handload.

Sealants
The main culprit in decreasing stored life of a loaded round results from corrosion. Some call it “sticktion,” and I’ve had it happen a few times. What it is, is the case neck and bullet corrode — stick — together. That will elevate pressure. I had a rash of blown primers from the batch I used.

There are a few ideas on how to reduce or eliminate stiction, and the first starts with eliminating the catalyst for the corrosion. Don’t touch the bullets with your bare fingers! Don’t touch the cases either. I know a few commercial loaders who produce precision ammunition and they’re all about surgical-style gloves.

I have run some tests using bullet sealant (applied as a liquid then UV-cured) and such a product will, indeed, virtually eliminate any worries over corrosion. Most factory, and virtually all mil-spec, ammo uses some formulation of sealant (bullets and primers). The reason I tried it, though, was because of the promise of greater accuracy. Glued bullets tend to produce from a little to a lot smaller velocity spreads. My jury is still out on the value of this additional step, and when there’s a verdict I’ll let you all know how it played out.

reloading sealant
Here’s a simple and easy sealant that works well. One bottle will last about 1000 rounds. Check it out at Midsouth HERE.

There are a few different bullet and primer sealers available. For the most part, these are fairly easy to apply and none are what I’d call expensive.

Giving loaded rounds a good cleaning, and then storing them at the least in air-resistant boxes, keeps the shine on and the corrosion away for a good long while.

Some run their loaded rounds in a routine-type case cleaner, like a vibratory tumbler. That’s all good, but I suggest not using anything but “pure” media to ensure that no residues are left behind.

I use denatured alcohol and a bath towel: place the rounds on half the towel, pour on the alcohol, fold over the towel and roll the rounds around. Let them dry and box them up.

Handling precautions during round assembly and then good storage afterward extends the shelf life of reloads.

More about another factory trick — crimping — next time.

The preceding is a adapted from information contained in from Glen’s books Top-Grade Ammo and Handloading For Competition. Available HERE at Midsouth Shooters Supply. Visit ZedikerPublishing.com for more information on the book itself, and also free article downloads.