Home Forums Hunting & Shooting AR and Tactical Rifles Crimp or not?

Picking up my first AR tomorrow. Got 500 new LC cases coming too.

Seems to be some difference of opinion on how necessary it is to crimp ammunition.

What say ye?

Thanks.

Never have and see no reason to start now.

I have no idea how many handloaded rounds I've put through AR's.

Ed

With sufficient neck tension, I've had no issues with uncrimped rounds.

I have far too much brass to keep it all separated closely by lot except for some small lots used in my more precision guns, therefore, there is always more variance in the neck springback / tension for all the rounds to have the same neck tension when the bullets are seated.

So, yes, I use a Lee Collet crimp die & very, very lightly squeeze the neck to, hopefully, a level that tends to somewhat uniform the grip on the bullet.

Hard & heavy crimps can cause other issues if overdone.

Ejecting a few unfired rounds occasionally & examining them for bullet setback from hitting the feedramps as the round is chambered might give a clue as to whether a crimp is needed or not.

MM

What Montana said. I put a very light taper crimp just to uniform neck tension and prevent any setback. Only takes a quick second to do and I don't have to worry about a loose one moving on me.

I read many articles and reviews before putting the Lee collet crimp behind the bullet seater on my press. The way the LCC works doesn't deform case necks unless you try very hard to. It may not be necessary but never found a test where it hurt either. It's one extra pull per cartridge is all.

It did nothing to hold in the Winchester 64 gr. PP's that I bought though. I kinda wanted those to work too.

I set all of my seating dies for a slight crimp, the AR is no different. This has been known to also help improve run-out and minimize TIR as well. Kind of like killing 2 or 3 birds with one stone, so to speak...

I never crimp rifle rounds, except for lever actions. I have the Lee FC die, so I guess I'll test my loads for good neck tension and crimp if needed.

One of the bullets I'm gonna try is one of the Barnes frangibles. I'm thinking too much crimp might not be a good thing with those.

Thanks, all.

not

Someday I'll work up the motivation to test a couple different loads crimped and uncrimped.....

I have and there did not appear to be a difference in groups.

I have with carefully prepared brass, same headstamp, same number of firings, trimmed and freshly annealed.
The uncrimped was more accurate, but not by a lot.

Ya gotta run the test at least 10 times, with 10 rounds/per, in order to be meaningful as one test don't mean jack schitt.................just sayin'

Seriously, I think it matters a lot as to how hard they are (over) crimped.............but if you are going to crimp, it does have to be enough to get uniformity.

MM

My main interest in this is whoopsie avoidance. Not expecting accuracy miracles from a 16" carbine, just good function.

have one AR rifle........Aero Precision 300 BLK.........

yes I crimp..........what does it hurt ?

Lee FCD..........nuf said......

The 5th station of both of my progressives sport a Lee crimp die.

Why not crimp if its a free motion as it is in a progressive

I'll bet I've shot 75+ K rounds in competition that I loaded, out of a match AR in 223 and never crimped the first one. Never had my gun have a FTF or failure to fire due to a round that tied the gun up due to bullet creep... Waste of time in my opinion...

There is a whole lot of ink on the affects on accuracy using the Lee FCD. Hard to find much negative.


http://www.accuratereloading.com/crimping.html

IF, there's any pushing the bullet deeper into the case as the round is pushed into the chamber, there will be more negative effect on accuracy than the potential loss of accuracy due to using a light crimp.

And unless you eject enough live rounds that have been chambered from the mag to know, then you really just don't know.

JMHO, YMMV

MM

+1 for the Lee crimp die. Run it on all ammo I build up that will be cycled in my ARs.