CRIMPING match rounds

wolf300H&H

wolf300H&H

CGN Regular
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Cabin in central Alberta
hey guys, have a quick questio for reloading.

so i bought a crimp die to go in the no 5 spot on my new dillion for slightly crimping 308 win for my semi auto springfierld ,question is should i use it on my target bolt rifle in 308 and crimp them as well slightly or moderatley or what? i will probably make a few test rounds crimped ,but just seeing what you guys have to say. its allready super accurate ,but will it increase/promote consistency and does it affect velocity ???

thanx for reading
 
In my experience the least amount of neck tension that will work yields the best accuracy in precision rifles. .002-.004 neck bushing dies seem to be the norm. Crimping is generelly reserved for self loading or tube fed guns.
 
IMHO, I am not a fan of crimping any time, unless it is absolutely necessary.

If you have proper neck tension, it shouldn't be needed.

Speaking of the semi auto Springfield. The US and other nations that used the M14 didn't see the need to crimp their ammunition. To my knowledge, you don't have a special match chamber on that rifle, unless you specified one when you ordered it or had it re chambered later.

As far as bolt action rifles go, even those with match chambers that require the necks to be turned down, don't need to be crimped. Neck tension in those rifles isn't used the same way as it is in normal rifles. The thin necks, hold the bullet straight until it is up against the leade upon chambering.

Most of the match shooters I know, seat their bullets out far enough so that the bullets are seated right on the leade and pushed back a few thou when chambered.

Also there are only a few matches that require more than one cartridge in the mag or on the feed ramp.

Some of the older 303 British, made for the military was dimple crimped for use in Brens. I've seen some older 30-40 and 30-30 crimped as well, but as mentioned that was done for tube and some mag feeders. It was common on some black powder cartridges as well. I'm not sure if that was to keep the bullet seated against the powder or to stop the bullets from being pushed back??? Same for cordite loads.

Lots of the older pistol cartridges actually had and many still do a mouth crimp. That seems to be another hold over from the black powder days as well. The 45LC is a good example. The old black powder stuff and even some later stuff has the crimp. Over the last 20 years or so, I haven't noticed any of the newly manufactured stuff with the crimp. Maybe Cowboy Action ammo still has it.

Another thing, unless you're crimping into a cannelure on the bullet. You may actually be doing some harm to your bullet by deforming it.
 
Longshot said:
Never had to crimp any match ammo I've made even when running it through semi autos.
Click to expand...

I know of one very accurate factory .308 round that uses a crimp 168 grains in IVI brass ring a bell;) According to the CGN experts it destabilizes transonic/sub sonic.lol

I bought a lee factory crimp die I will report my findings when I get a chance to test it out:)
 
I crimp everything. Lol.
I've had decent luck with ammo produced for both bolt and auto guns. I feel based on testing I've done I get better uniformity and less velocity spread with a light crimp.

Below is a crimped 77gr. SMK beside an un-crimped bullet.
There is no deformation beyond the slight impression of the crimp which is not as deep as the rifling grooves that are going to be made as the round passes down the barrel.


 
I have not experimented for accuracy with crimping, but I did experiment once with neck tension. More tension got better groups.

I would not be surprised to hear you report that with ball powder, a crimp helped accuracy.
 
If my hand loads need to be crimped, something is wrong. I have fired thousands of rounds of uncrimped 223 out of AR's and I have never had any issues. I have found that they tend to be more accurate without the crimp too.
 
DG Photography said:
I know of one very accurate factory .308 round that uses a crimp 168 grains in IVI brass ring a bell;) According to the CGN experts it destabilizes transonic/sub sonic.lol

I bought a lee factory crimp die I will report my findings when I get a chance to test it out:)
Click to expand...

Hahahaha!!
 
DG Photography said:
According to the CGN experts it destabilizes transonic/sub sonic.lol
Click to expand...

Check out B.Litz' commentary on the 168gr Sierra. It's actually before the transonic region.

Others (Ron/Jim/Mike) - agreed on the neck tension - I find with coated bullets that more tension works better. Crimping does the same thing, just not as well, as adjustments are more finicky being focused on the end of the brass, not the entire neck (more variable due to the OAL of the brass itself).
 
thanx for all the info guys. seems like its just a pistol thing then. i have 64 rounds for the m14 i made on the dillion with a little crimp, 4 im gonna shoot in a bolt gun just to see if it like 150 gr . but ill check for accuracy and velocity with the semi and slightly crimped rounds next chance i get.
 
"...unless it is absolutely necessary..." And it's only necessary for heavy recoiling cartridges(like your .300 H&H) and for lever actions. Match ammo doesn't need it and it is detrimental to accuracy.
 
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