Need help loading 175gr hpbt for AR10

[powerstroke79]

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

[Great-Kazoo]

The links are geared for the M1A not the AR rifles. However it should give you an idea .


http://forums.thecmp.org/archive/index.php/t-147483.html

scroll down to sailormilan2's post.

There's different data for service rifle (auto loaders, M-1'A) in hornady's load data.


http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

http://bearblain.com/Service%20Rifle%20Loadings.html




My Sierra manual is not handy at the moment, later i can check to see what if any info they offer for service rifles.

[Zombie Steve]

All of those variables come in to play, but the load development doesn't change that much. Start low, work up slow watching for pressure signs. You will likely find your max before the listed bolt gun data. Where that point is can also depend on the gun, the temperature, differences in primers, etc.

Are you putting it over a chrono?

[Hoser]

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.

[jmg8550]

I load 42 grains of 4064 in a Federal case, or 43.1 grains of RL15 in a military case and a 175 bullet for my match M1A. These are essentially FGMM, and M118LR duplicates.

[Zombie Steve]

Regarding bumping the shoulder - Hosehound is right on the money, but it's easy to overdo it. Too much and you're destined for case head separations. $28 for a .308 case gauge is well worth it. Proper headspace is really damned important. Take it from the guy that learned it the dumb way. I mean, uhhhh, I had this idiot friend that did this and then told me about it. :whistling:

[Hoser]

$28 for a .308 case gauge is well worth it.

Or you can always use your rifles chamber...

[powerstroke79]

Thanks for all the input. Made two runs IMR 4064 40.1-42.9 went up .3 gr at a time. 2nd Reloader 15 38-42.8 went up .3 gr at a time, Coal was 2.800. Down loaded max load on both 1gr because I used lc brass.

[jmg8550]

I've seen pressure signs using commercial brass with 42.5gr of 4064, with LC you might see them earlier. After 42gr, I'd start watching closely for too much pressure.

With RL15, 43.1still isn't too hot even with LC brass. With Hornady cases, it only went 2570 out of my 24" Savage.