AR-10 308 win.

Im loading 165gr sp w/about 40gr. Should i crimp them???

You'll probably get 50/50 on opinions on that. I don't crimp but that's just me.

I don't crimp any of my AR loads. I do crimp some monolithic loads. Others swear by crimping.

In my opinion, if you go through a mag and the last round still has the bullet at the original position, you're good to go!

I have always done a light crimp with a Lee crimper.

just process your brass with your desired neck interference (i.e. tension) and load away.
I don't crimp any of my rifle loads.

One cold morning I went to extract an unfired round. Case came out, bullet stayed in. This was supposed to be 0.010 off the lands. After that I started crimping everything. Before, I only crimped 376 H&H

jhites said:

Im loading 165gr sp w/about 40gr. Should i crimp them???

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After your first shot extract the round that is just fed and check the OAL/CBTO and see if anything's changed. I put a light crimp on all my AR loads after experiencing OAL growth.

Have you rectified the other issues you've been having that are mentioned in your other thread?

I pretty much crimp everything that goes into a mag except the ammo that I shoot out of my 20" bull barrel AR upper, which gets single fed. Mostly that's because it's got a light trigger and will double tap if I don't single load. But it's my most accurate AR so it gets babied in every way.

Even bullets without a cannelure get at least a slight crimp and I've never had any problems with bullet creep. My AR rounds get "crimped" with an old cut down neck size die that I use to put a 1/8th inch crimp on everything that will be fed from a magazine. On the AR10 I would use a regular crimp die and put a slight crimp even on bullets without the cannelure. The heavier the bullet the more the need for a crimp. I test by taking the last round in a mag and run it thru 3 mags, including chambering and extraction, measuring the OAL after each mag. If there's no creep, I feel it's good to go. In addition, I do not use an expander ball or mandrel for 'regular' rounds except those loaded specifically for accuracy. I want as much neck tension as I can get, short of glueing the bullets in!
Cheers,
crkckr

jpd676 said:

I don't crimp but that's just me.

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The same here. I have a few crimp dies, but I have yet to find the need to use them.

I do not crimp my 308 rounds for my M&P 10. I haven't seen the need, especially with bullets w/o a cannelure. If you're concerned about creep, perhaps a taper crimp.

Taper crimp is all I use except on revolver rounds and even then, the only thing that gets a roll crimp are 38 Special self defense loads (and anything bigger). All lead or coated bullet loads get taper crimped, even on the .44 Mag.
Cheers,
crkckr

jhites said:

Im loading 165gr sp w/about 40gr. Should i crimp them???

Click to expand...

My AR-10 308 has such light recoil (and most do) that I have never considered doing crimped bullets.
In fact, I have never crimped any of my rifle loads except .458x2" with 405gr. lead.

as long as you don't have bullet setback or kinetic extension/lengthen, then it's not necessary. i crimp everything including ba ammo. all just a preference.

If the cannelure is in the right place for me, I'll use it. I gently flare all my case mouths, so I use the LFC to "iron out" the flare. I wouldn't call that a crimp though.

I also own an Ultimate Cannelure Tool. This thing makes the Corbin version cry. I don't think you can get them anymore. I can put a cannelure wherever I want on any bullet, even a copper or bronze monolith. But who would want to?

I used it primarily to give me the full use of the long cylinders on my Ruger revolvers. Then I went almost 100% cast. It was amazing for experimenting with the 45 Colt in the Blackhawk Hunter.

I am using it again on my 358 Norma loads. Not changing the BC much on a 310 grain RN by adding a crimping groove.