Crimp or Not

[RAF]

I neck size all my once fired brass that I load for my bold action rifles. I haven't crimped them and got wondering today what others do.

[wilmsmeyer]

There should be no need to crimp IMO. Proper neck sizing provides enough "hold" on the bullet. Most rifle bullets do not come with a cannelure which provides a nice place for the crimped brass to rest in without "pinching" the bullet.

To test your particular ammo out do this: Caliper a magazine full of your reloads for overall total cartridge length and write the number down. Load your magazine full and cycle them through the gun as you shoot. Take the last cartridge out without firing it and caliper it again for overall length. Chances are it will be the same length.

[RAF]

I use a Lee crimper which, according to the directions, doesn't need a cannelure. I use it bullets loaded for an autoloader, and lever action. I was just wondering about it for the 300 WSM as I approach the max powder load I'm approaching a compressed load.

[youp50]

I crimp them all. I shoot lots of Hornaday bullets, most have a cannelure. The Barnes and Sierras get a Lee factory crimp. I bought into Lee Precision's reasoning for crimps. Most factory loads are also crimped.

I have never experimented with the crimped vs non-crimped velocity spread so I can't say. I quite sure that I am not hurting anything by crimping them.

[antleraddiction]

I see no need to crimp for a bolt action, unless a extremely heavy recoiler (which the likes of 300 does not apply). Semi or tube feeds sure.

[whyohe]

on my 30-06 i did not crimp even if it had a cannelure.and i got sub MOA on my reloads. the only ones i crimped was my 44 mag wad cutters and the heavy pressure loads.

[art338wm]

About fiftten years ago when i first started to reload for rifles, I also wondered if i shoulkd crimp my reloads in 7mmSTW or my .338wm. I called Redding and spoke to one of their CS reps. He assuered me crimping was not nessasary till I got into calibers that recoiled much more than my .338wm.

Just to be safe I reloaded five rounds of .338wm with out any powder or primers and kept them in my rifle for well over 50 firings, or ten each. I later measured them all and found zero bullet movement what so ever.

[mistered]

Very few situations require crimping. Tubular magazine is one. The advatage of not crimping is that the case mouths will have a more consistant tension on the bullets. Crimping requires exactly the correct length case to be consistantly done.
-Ed

[RAF]

mistered, you're right about brass having to be the same length but only if you're using the crimping feature of the seating die. With the Lee seating exact length is not an issue. Lee claims their die duplicates the factory crimp. I don't know about that. However, it's been my experience that consistency is an issue. So if you crimp, even for a bolt action rifle, then it should be done all the time. If not, well you know . I decided to crimp because the 300 WSM recoils pretty good. If something recoils much harder, I don't want anything to do with it ;D

[harley]

RAF, I just stumbled across this old thread and don't know if you check back on it or not, but wanted to add my experience with crimped vs non-crimped loads.

I shoot 7MM-08, 300 Win Mag and 30-30 WCF in a Contender G2 pistol. I've never crimped for the G2 because it is single shot and isn't vulnerable to recoil-induced seating shifts. I've always crimped my other cartridges with a Lee Factory Crimper, never the seating die (couldn't if I wanted to because I use the Redding Competition dies and they don't have a crimp adjustment in the seater).

Here's what I discovered this past year:

1. Crimping with the Lee crimper definitely increases bullet-pull tension, to the point that group velocity has less fps variation than when uncrimped. That's a good thing.
2. Crimping adds up to .002" to the OAL, so bear that in mind when setting up.
3. An uncrimped bullet in the magazine will definitely change in OAL when the 300 Win Mag is fired, and to a lesser extent the mild 7MM-08 as well. That's a bad thing.
4. A Lee crimped group is not as accurate (will not yield smallest groups) as an uncrimped group. I think this is because the crimper does not crimp each cartridge exactly the same as the one before. I KNOW it's because the crimper throws the bullet off center. You can prove it to your own satisfaction by checking for empty case run-out, then comparing that with a loaded cartridge run-out both before and after crimping.

So, I've stopped crimping. It doesn't hurt the G2, I'll ignore the slight shift in the 7MM-08, but am considering shooting the 300 Win Mag as a single shot. No good solution there.

[Jeremy]

I'm no expert reloader by any means. But I have been playing with my Stevens 223 this summer and I have found that the pet load that I have developed shoots better when crimped.

28 gr BLC2 and a 50 grain V-Max gives me groups in the .500" to .600" range day in and day out - while the exact same load un-crimped hovers right around 1 inch. Not huge difference - but enough to convince me to run each load through the crimper I found the same think with many of my other loads (not all mind you). Varget was the exception for me - both crimped and uncrimped loads shot nearly the same.

I think that the crimp improves uniformity - and that is why I use it. Obviously it also maintains COAL in heavy recoil guns - which is a seperate but notable benefit.

Ultimately - it comes down to your individual load and what the crimp does to affect it.

[harley]

Well said, Jeremy - whatever works in an individual situation.