.223/5.56 77gr precision loads - to crimp or not to crimp?

[TheGerman]

Loading for my Mk12Mod1 with 77gr projectiles. Nothing out of the ordinary with the round, 2.26 OAL and I use Redding S type dies to give it a little extra/uniform neck tension at .244 for this specific combo.

Question is, I crimp my run of the mill 55gr rounds that go into my carbines and that die is in a different toolhead. So either I need to get another die if I should crimp these or leave it alone as these are geared towards precision but will be fired out of a 20 round magazine, magazine fed and on semi auto.

ETA - projectiles do not have a cannelure

 

[InfScout1/69]

If you have enough next tension you don't need to crimp. You just have to figure out how much neck tension you need to negate crimping

 

[elfster1234]

No crimp!!

Loading for my Mk12Mod1 with 77gr projectiles. Nothing out of the ordinary with the round, 2.26 OAL and I use Redding S type dies to give it a little extra/uniform neck tension at .244 for this specific combo.

Question is, I crimp my run of the mill 55gr rounds that go into my carbines and that die is in a different toolhead. So either I need to get another die if I should crimp these or leave it alone as these are geared towards precision but will be fired out of a 20 round magazine, magazine fed and on semi auto.

ETA - projectiles do not have a cannelure

 

[Steel head]

No crimp or a very light crimp with a Lee collet.
I personally don't crimp and run .003 of tension for my 75/77/8208XBR AR loads and never have any issues.

 

[TheGerman]

No crimp or a very light crimp with a Lee collet.
I personally don't crimp and run .003 of tension for my 75/77/8208XBR AR loads and never have any issues.

I'm running .002 with the Redding bushing.

Looks like I'll run them without a crimp.

Thanks guys.

 

[gunsnjeeps]

Good call. I don't crimp for my NMA2's.

Steel Head what powder weight are you running? I'm getting ready to workup 8208, shifting from Varget (loading on T7)to progressive loading 8208 in a 650.

 

[stockdoc]

No match or precision ammo should he crimped.

 

[waltere]

I have seen a crimp help and I have seen it hurt. If what you are doing is not shooting for you, try a crimp.

 

[dvdt]

Just to add another data point...

I crimp my 55gr stuff.

I do not crimp my 'precision' loads. I shoot several different bullets but do not crimp any of them. I'm also running .002 - .003 neck tension / interference fit

No problems so far but as you mention, I'm also using 20rnd mags.

 

[Diesile]

No crimp or a very light crimp with a Lee collet.
I personally don't crimp and run .003 of tension for my 75/77/8208XBR AR loads and never have any issues.

X2

 

[DrewC]

I use a Lee factory crimp die and it's set for a very light neck squeeze. The collets don't touch each other and you cant see any noticeable markings on the neck. It tightened up my groupings a tad. I don't touch it and run all my ammo the same way.

 

[lazyengineer]

Depends on your goals. I actually kind of like crimping - for some ammo. For what it's worth, when I shoot reduced 200 yard high power matches, I use Hornady 55 gr ball projectiles, and I crimp with Lee FCD. Shoot good to me - I shot a 488/500 last week, with only three 9's on the reduced slow prone - and doubt it was the ammo. Will it make the difference between an X and a 10? Not sure - maybe.

But that's at 200 yards, so not all that serious anyway.


For my 600 yard loads, I don't crimp, but am testing the Redding bushing die, which basically pre-tensions the entire neck. I was able to get a 1/2MOA group at 200 yards with 80gr SMK's doing that. For those bullets, crimping probably isn't the best idea.

In short - if it has a cannular - crimp. If it doesn't - probably shouldn't most of the time.

At least, that's just my opinion. But I'm still learning: only Expert class and not Distinguished (yet!)