Quote Originally Posted by powerstroke79 View Post
Need some help. Try to develop a load for a 18 inch AR10 using Sierra 175gr hpbt. Powders I'm using are IMR 4064 and Reloader 15. After hours of the great Internet and looking through a couple mauals I have, I'm more confused then when I started. Most loads I found look to be for a bolt gun and not a gas gun. My other confusion is the nato brass to commercial brass.

So some questions I have are
1 Do you guys back down loads for gas guns? If so 1 or 2 gr?
2 Nato brass down load 1 or 2 gr?
3 Do you make 1 load for nato brass and another for commercial brass?
4 If you down load for a gas gun do you also need to down load for nato brass

Like I said more confused then when I started.
Thanks for the help
1. Yes. And sometimes lick powders that burn a little faster to ease up wear and tear on gun. Slow powders beat up the gas system more than faster powders. Much more of a concern with M1A/M-14 rifles than with an AR-10.
2. Not normally. NATO brass is normally thinner/lighter than Commercial brass so Uncle Sam can jam more powder in to drive up velocity.
3. Nope. Whatever brass I get decent accuracy with is what I stick with.
4. See #2.

Start with a mild load of RL-15 and load them as long as you can and still fit in the mag. If it is accurate and the gun functions, then your load development is done.

When FL resizing your brass, if it won't resize enough to fit in the chamber, be sure to get the shell holder bottomed out then add 1/8 - 1/4 turn more (cam over) to bump back the shoulder and resize the base.

You do not have to crimp. Really. You do not have to crimp. You can easily destroy accuracy in a heartbeat. If you decide to crimp, just barely crimp it.

If you use GI brass with crimped in primers, get in touch with me. I can run it through my 1050 and get that taken care of.