Crimp or not to Crimp ?

By default I used to lightly crimp everything, but it caused huge velocity spreads for me in my semi auto 6.5 Grendel (123gr sst with Canelure) For troubleshooting purposes I did a batch without a crimp and my velocity was much more consistent. After that, I only crimp pistol cartridges.
 
When I started reloading a year ago, I was going off just what I read in the manuals. It said to crimp "heavy recoiling loads" but did not quantify what they considered heavy recoiling. So I was crimping the 308 loads I was doing. After more learning I learned it wasn't necessary. Didn't change anything about the loading, and only stopped crimping. At least for my rifle and my loads, my groups stayed identical. So I didn't have to rework anything and now I save a step when loading
 
I've had decent success and accuracy loading 'factory style' ammunition for rifles I didn't want to spend much time on. Quality projectile and case, powder with a suitable burn rate, load to SAMMI OAL, crimp with LFCD. Sub-MOA more often than not. Loaded some 243 for my wife's Tikka last night, and will test the theory again next range trip.

No crimp usually tho, other than leverguns.
 
what about .303 british?
Most 303 bullets in my reloading stash have a fairly generous area at the crimp location.
I bought a lee crimp die just in case. Haven't started the reloading yet but was curious about crimping.
I also plan to reload for the 7mag and so far a good friend has worked up my loads for me in this rifle. I'll have to dig out a box of the reloads and see if there is a crimp LOL

good thread.
 
Crimping has improved accuracy for me in guns that have a really long throat. It’s another tool in the reloading tool kit that I use, but rarely.
 
I crimp revolver loads, cast bullet loads (which covers my tube feeds) and 458 Win and Lott. That's actually quite a few I guess.

Other than that, nothing. Most of the bullets I use don't have grooves, and the dies I use on favorite calibers don't have a crimp function anyway.
 
I crimp revolver rounds. The bullet pulling forward on recoil can jam the gun.

I crimp ammo used in a tube mag.

And I crimp ammo loaded with ball powder. It usually improves ignition and accuracy.
 
Never crimped any rfile round.

Before I sold my Modern Sporter, I was reloading 223 for it.
The barrel that ATRS made for me was beyond ridiculously accurate.

However, being it is semiauto rifle, I had concerns that the force of the bolt slamming forward and/or feeding ramp may change the CBOT from shot to shot.

I reloaded to maximum CBOT I could go with a 77 MK for a LAR magazine.

I repeatedly tested rounds before chambering and after chambering... as expected they moved.
Moved anywhere from 2 to 4 thousands forward.

I don't think it even did anything detrimental to the accuracy of the gun.

But being Type A that I am, I still wanted to solve this "perceived" problem that I had anyways.

Moving from a 2 thousand neck tension to a 4 thousand neck tension was enough a solution to the perceived problem that CBOT did not change before and after chambering.
 
Last edited:
For the last year I have been giving a slight crimp in my cartridges. I noticed a drop in my ES/SD. I think from a more consistent neck tension. I could be out to lunch though
 
I crimp .22 Hornet since it seems to respond to crimping because of the very thin case. I crimp some bottleneck cartridges like .308 with Barnes 130 TTSX - the very short bearing surface of that bullet makes crimping improve consistency and is recommended by Barnes. I crimp a few hunting rounds that are loaded for rough use / wilderness survival type situations, not because it's necessary, just because it makes me feel better. And some reduced, cast bullet loads because it seems to improve consistency of ignition. And I crimp .375 H&H, and .450-400 3" Nitro Express because recoil may move the bullet and since they may be used for dangerous game hunting.
 
I crimp pretty much everything. My own testing showed improvements in accuracy so why not? Better groups and ES/SD. I don't do any formal precision or long range shooting though.
 
Ah, I'd forgotten about the 44 mag lever action, crimp those.

For bottle necks, I crimp Hornady 55gr FMJBT in .223 Rem as it gives a cleaner powder burn.

My 9.3x62 with 255 gr Geco softpoints gives a cleaner burn with N150 (Quite a short, stubby bullet - not a full length of bearing surface in the neck)

The 7mm GMX I load for my Dad he says a slight crimp shoots better for him.

Scrummy
 
You must log in or register to reply here.
Back
Top Bottom