I don't reload and was asked a question about case crimping...What are the advantages, disadvantages. Is there a difference in accuracy? Would it make more sense to crimp semi-auto loads or what?
Crimping the bullet in the case?
- Thread starter Rade1MOA
- Start date
As with most things...it depends. Crimping increases consistency in neck pull (in most cases) and helps when a chamber has a long throat to allow a more uniform ignition due to increased neck pull. It is not an absolute, as every rifle that i have seen that has shown an improvement with a neck crimp, I can point to another rifle that shows no improvement, or in some cases, a decrease in accuracy.
IMHO, crimping is one of those things you turn to when tweaking a load for accuracy improvement or in firearms where the recoil hammers the ammunition around in the magazine and/or when insertion into the chamber can be rough.
JMTCW...
IMHO, crimping is one of those things you turn to when tweaking a load for accuracy improvement or in firearms where the recoil hammers the ammunition around in the magazine and/or when insertion into the chamber can be rough.
JMTCW...
Rade1MOA,
There's a few instances wherein crimping is absolutely necessary, and a great many where it's not. Revolvers need a crimp, especially if there's a heavy recoiling cartridge involved, or else the bullets will pull under recoil. Tubular magazines are another, where the bullets need to be absolutely secured in the case to prevent set-back while in the magazine. Most auto pistols need a slight taper crimp to assure proper feeding. As far as most semi auto rifles, no, and they'll generally shoot better without being crimped. In some situations where the ammunition may be treated very harshly, the trade off in terms of loss of accuracy is worthwhile, which is why most military ammo is crimped to some degree. Still, the rounds intended for accuracy (even military rounds) generally have the absolute minimum amount of crimp they can possibly get away with. Accuracy minded shooters tend to avoid crimping in almost all situations, as it's just another variable to contend with. Stick to proper neck tension, and you'll be better off.
There's a few instances wherein crimping is absolutely necessary, and a great many where it's not. Revolvers need a crimp, especially if there's a heavy recoiling cartridge involved, or else the bullets will pull under recoil. Tubular magazines are another, where the bullets need to be absolutely secured in the case to prevent set-back while in the magazine. Most auto pistols need a slight taper crimp to assure proper feeding. As far as most semi auto rifles, no, and they'll generally shoot better without being crimped. In some situations where the ammunition may be treated very harshly, the trade off in terms of loss of accuracy is worthwhile, which is why most military ammo is crimped to some degree. Still, the rounds intended for accuracy (even military rounds) generally have the absolute minimum amount of crimp they can possibly get away with. Accuracy minded shooters tend to avoid crimping in almost all situations, as it's just another variable to contend with. Stick to proper neck tension, and you'll be better off.
I crimp all my rounds loaded for gas guns. I have 6 ARs and an M1a. I use the Lee crimping tool. A light crimp is an insurance policy against bullet set back. Military gas operated semi auto rifles are designed to act rather violently to insure reliability. Projectile set back can lead to dangerious high pressure and this occurs just a few inches from your face. I have done extensive testing with my AR chambered in 6.8 spc and have found that crimping did not effect accuracy nor velocity to a measurable degree. I do not crimp my bolt action loads.
