crimp or not?

I only crimp when I have to.

I only crimp if feeding from the magazine if shooting one at a time no crimp.

I prefur to crimp. At the very least it is a more durable cartridge, my offer a bit more uniform ignition. With that said, it may work fine without, i have had good results either way.

I used to be a crimpahaulic... but I've gone to therapy and I'm doing much better.

If you are looking for maximum accuracy and/or consistency, don't crimp. As long as you have proper neck tension, a crimp is not required, and a crimp at this point may even hurt accuracy and/or consistency. Deforming the bullet with a crimp, and bulging the case neck with a heavy crimp (if, for example, the case is a wee bit long compared to the others...) are the usual culprits.

Do I need to crimp for a semi-auto? No, but, again, you have to have proper neck tension for this to work. I've even gotten away from crimping my match ammos for my AR's, and my M1a and M1 Garand. I would never crimp anything going into my bolt guns.

Yes, I crimp bullets going into my tubular-feed lever-actions. I do not crimp bullets going into my rotary-feed Savage 99 lever-guns.

The caveat to crimping rifle cartridges is with cast. Because you have to bell or flare your brass with something like a Lyman M-die... to help start a cast bullet, keep it straight, and not shave lead... you usually have to knock the flare back in after bullet seating. If it's going in my single-shot breech-loader, I just knock enough of the bell out to chamber reliably. If it's going into one of my lever-actions, I roll that case into the crimp groove.

I crimp anything that goes in an auto loader or lever gun.

I crimp revolver ammo and any ammo that might be loaded into a tube mag. Everything else, no crimp. Almost all of my semi-auto rifle rounds use match bullets, which don't have a crimp groove. Although I guess technically I lightly taper crimp auto pistol ammo, but that doesn't really count as a crimp to me.

For a bolt rifle, I haven't found any real world pros to crimping.

I only load for everything that is supposed to be crimped: lever actions, revolvers, and auto loaders. Therefore I crimp everything with a minimum crimp, except one. My Sierra Match King load in my 308 gas gun doesn’t get crimped. I did make a dummy round and run it through the action dropping the bolt every time for three or four cycles. It actually grew about 0.001” each cycle. Now I know to watch for that.

It's all about neck tension and how you load.

I crimp my blaster ammo AR ammo, because I run an M-die in station one to make it easier for the bullet feeder. But that's only a kiss to remove the flare. It's probably not enough to majorly affect neck tension.

For anything loaded for accuracy, bolt or semi, I never crimp as I anneal every firing to ensure proper neck tension. That doesn't matter if I'm running a single stage or progressive.

I crimp if the bullet has a cannelure. Those are usually bullets that I am using for plinking ammo. Even at that it is a very light crimp.

The only thing I crimp is rounds for tubular magazines and revolvers. None of my rifle ammo for LR-10 or AR15 are crimped, i use 0.003"-0.004" of neck tension. Years (decades) ago I tested for accuracy, crimp vs un-crimped, Un-crimped won every time in my test. Recently I tested it in 357sig, the crimped ammo opened up the groups by 50%. So I don't crimp that little bottle neck round. Getting high neck tension on a 357sig takes some work since your working with a very small neck area. This is one round that you want to use a powder to fills the case to keep the bullet from moving during feeding. Remember crimping removes neck tension, not increases it when not crimped into a cannelure on the bullet to hold it..

I crimp for most rounds.

Only for lever guns

I crimp everything. Amount of crimp depends on the bullet.

For my bolt guns I don't crimp (308, 7.62x54). Normally when doing a load work up I will fill the magazine shoot all but the last round, chamber it, extract and measure. My single shot rifles, no crimp. My semi-autos are first checked with the above method, load the magazine and measure the last round. Any bullet that moves gets a light crimp and test repeated. With military brass my Garand will usually work OK with no crimp

I use a "light" crimp for semiauto rifles, revolvers and tube fed guns. I might tighten down the FCD 1/8th turn after kissing the flare for 223 and 6.5 Grendel trying to get the neck outside consistent, with 30-30 I like the mouth to be less diameter. For my bolt actions the only ones I crimp are the ones that have a cannelure. My idea of crimping is just to uniform the neck more so than trying to indent the bullet

Crimp autoloaders and straight walled cases only.

I compromise. If the bullet has a cannelure, I crimp. If it doesn't, I don't.

I only load 223 and 9mm. I haven't found the need to crimp with 223/5.56. I do use a taper crimp to remove the 'bell' on 9mm though.

I do not crimp bottleneck rifle rounds

Lee used to claim their factory crimp die improved accuracy






Lee Lied:



Only crimp when you have to. I crimp for lever action rifles, pistol rounds, especially 45 ACP. Not going to notice any diminution of accuracy in a pistol. I never crimped my match ammunition for AR15's, M1a's, or Garands. Nor for any rifle that recoils less than a 375 H&H.

Something with this much recoil:crimp!

Slamfire said:

Lee used to claim their factory crimp die improved accuracy

Something with this much recoil:crimp!

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I don't crimp my 375 Ruger rounds and so far no issues

sisyphus said:

I don't crimp my 375 Ruger rounds and so far no issues

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My 375 H&H loaded with 235 grain bullets would seat the bottom bullets in the stack. Maybe they had more running room. I have not fired enough full power rounds in the 458 Win Mag to test bullet seat back. The thing hurts to shoot.

No crimp on bolt action rifle cartridges, with the exception of BIG DGR cartridges.

Only crimp 44 mag and 50AE. Don't load anything for tubular mags right now. Deer rifles, AR's, 9mm, etc... no crimp. 9mm only gets neck expanded (jacketed bullets), no bell mouth, so no need there.