To Crimp, or not to crimp?.

[USMCM16A2]

Gents,


I am planning a trip to the range soon, so I would likre to take a standard 5.56, 55gr BTFMJ with me. I roll my own, I will be using Remington once fired brass, 25.3 grains of H335, a CCI-41 small rifle primer, topped by a standard 55gr BTFMJ bullet OAL of 2.24 inches. My question is do I need to crimp?. The RCBS die set I have is their standard 2 die set. It is suppossed to be able to provide a roll crimp in the canneleur. I have succeded in my experiments (after reading the booklet) in crushing numerous cases. DO I NEED TO CRIMP?. Thanks, USMCM16A2

[ar15barrels]

My question is do I need to crimp?. The RCBS die set I have is their standard 2 die set. It is suppossed to be able to provide a roll crimp in the canneleur. I have succeded in my experiments (after reading the booklet) in crushing numerous cases. DO I NEED TO CRIMP?. Thanks, USMCM16A2

When loading bullets with a cannelure for semi-auto guns, it's good practice to crimp.

You just need to learn how to adjust the seat/crimp die.
As you turn the die body down to increase the crimp, you have to unscrew the seating stem by the same amount or you will be jamming the case mouth into the top of the cannelure.

Try it this way:
Seat a bullet into the case without a crimp.
Turn the seating stem up a few turns,
Slowly turn the die down while repeatedly operating the press handle.
You will eventually see a crimp starting to form.
Continue until you see the crimp you like and then lock the die lock-ring against the press.
Now run the ram all the way up again and snug the bullet seating stem against the bullet and lock the seating stem in-place.

This should give you a correctly adjusted seat/crimp die.
Try another case with a bullet and you should not have the shoulder crushing problem.

[hybridatsun350]

What will you be shooting? An AR?

If so than you may want to. Most people prefer to crimp when shooting an autoloader. If it's a bolt .223 than you don't need to at all.

[want_ar]

Crimp for semi-autos. As has been pointed out, Lee's factory crimp die works best.

[xrMike]

What if the bullets you're using don't have a cannelure? You still crimp?

[PistolPete75]

i've crimped, and not crimped for semi-automatic loads. my verdict, no need to crimp.

[ocabj]

I only crimp if it has a cannelure, and the only time that happens is if I'm reloading 55gr FMJ.

If it doesn't have a cannelure, then any crimp that you put on the neck to make any sort of difference in keeping the bullet in place will damage the jacket.

The military made a big deal about having a cannelure ring on the 77gr bullet for the MK262 spec ammo. Sierra ended up doing it, but they even admitted that the cannelure ring they applied on the 77gr Match King used for MK262 is more cosmetic than anything and doesn't serve much function for a true neck crimp. From the Sierra 77gr MK that I've seen with the cannelure, it does look very light.

[ar15barrels]

What if the bullets you're using don't have a cannelure? You still crimp?

Taper crimip.

The most important thing to get consistent crimps is to have consistent brass trim lengths.

[grywlfbg]

I have a Dillon 650 and w/ their 3-die set the last one is a taper crimp. I'm using Hornady 55gr FMJ-BT's w/ a cannelure in an AR so I apply a taper crimp. It's not quite as strong as factory ammo (I've been able to shove the bullet back if I place it against the edge of my bench and lean into it) but it's been plenty strong for all of my competition work including dropping full mags onto concrete.

I like the peace of mind from having crimped ammo but haven't felt the need to step up to the Lee Factory crimp stuff.

As Randall said, make sure your cases are trimmed to the same length. I had some weirdness with some of my loads until I bought my Giraud trimmer. SO happy with that purchase. I can plow through 1K rounds in a couple hours now. :gunsmilie: