To crimp or not to crimp

[KillBilly]

Good info

Is it safe to assume you've given a round too much crimp if its alterred the shape of the bullet at all, or is some ok/to be expected?  (i.e pinch it inwards slightly at the crimp point)

If you follow the instructions on setting your dies, you will not deform any cases. In some instances, I use a seater/crimper and for other applications I use a crimping die after seating. if you get deformation, re-set your die.

[sakoshooter]

I don't crimp any of my rifle ammo.

[JackOfAllTrades]

I don't crimp my bottleneck rifle ammo either, but we need to realize that we're discussing this with a new reloader. The books say to crimp. The die's are designed to crimp.

We should support that.  If we don't, we should explain why we do not, to teach the new reloader reading this thread.

I do not crimp my bottlenech rifle loads because they are not fed in a tubular magazine and I have experienced less standard deviation of bullet velocities for my reloaded/chronographed cartridges, leading to better accuracy.

-Steve

[Heredoggydoggy]

if you don't crimp you can actually rattle/vibrate your rounds back into the case. I have read that all hunting rounds should be crimped and the primers sealed to prevent any moisture from getting in. I don't seal my primers but I do crimp every round I load.

When I first built my 7MM STW, it was still wildcat and I had a guy from Michigan professional loading my ammo for me. He did not crimp any of it and I lost a bunch of rounds due to the bullets falling back inside the case mouth. So, I always crimp every round I load.

If your bullets rattle/vibrate back into the case, it means the brass is too hard to adeqately grip the bullet, and the case necks need to be annealed.  If you notice, all the military Lake City brass has a heat coloration on the neck of the brass.  this is due to the annealing process, presumably to insure that the case necks are not too hard to grip the bullet, and jam the gun in the heat of battle.  Annealing is a simple process that can be done at the home shop, if needed to soften case necks.  I once had a lot of 30-30 brass that had necks so hard they wouldn't even hold a crimp.

[timberghost72]

Thanks for all the info guys. Looks like I am going the right direction. I'm gonna hold off on crimping my rifle rounds and keep the crimp on the pistol rounds.

[JimmyHoffa]

I get the opposite as Jack of All Trades...I find that crimping reduces my SD.  Also, find that primer types help reduce the SD.  So not sure how much of my variance is due to primer and how much to crimp.  Whenever I have a cannelured bullet I'll crimp.  Most of my hunting ammo is cannelured.  The weird fancy bullets I have don't have cannelures so, it's not an option for my press.

[JackOfAllTrades]

Whenever I have a cannelured bullet I'll crimp.

I should have caught that one.  I said "I don't crimp my bottleneck rifle ammo". I would if I reloaded 30-30 for tubular magazine. If the bullet seating depth is such that allows a crimp into canelure, I would, such as I used to for my son's 243 (sold it), that liked Remington Corlokts crimped in the canelure. That said, there is one bullet that I use for my 30-338 that has a canelure but the OACL is such that the canelure is well out from the case mouth. I do not crimp that bullet.

JimmyHoffa may not experience the same SD that I do, but realize that I only neck size fireformed brass, trim by hand and use a case runnout comparator to assist in creating the most concentric and uniform cartridges as possible. The concoctions fired through my rifles are quite refined.  Rifles/bullets/loads are different. Some like that jump to the lands. Some like to build a little pressure early. Some like a slower burn down the barrel. It is the quest of the reloader to find the sweet spot or recipe that works just right.  What works right in one rifle/barrel, may not be the ticket for another.

-Steve

[JimmyHoffa]

Yeah, some guns like different things.  With the exception of measuring run out (lack of tool), it sounds like we prep the cases similarly.  Heck, I even have a process for primer pockets and the flash-hole.  And polishing the inside of the case.  I've been tempted to put something like a Barnes TSX on a mini-lathe or something....just so I can crimp those too!