Home Forums Hunting & Shooting AR and Tactical Rifles AR10 in 308 load question

I'm well versed in making proper ammunition for the M1A, but I don't know much about the AR10.

With respect to powders and charge levels is the AR10 just another 308, or does it live in a smaller operating range like the M1A?

It's not a bolt action, but it's not an M1A either. You don't have to worry so much about gun damage, just brass damage. I'd keep it to faster powders like Varget, 4895, etc. unless you know you have a tuned gas system so you don't rip rims off. But it can take pretty hot loads, one of my favorites being 45gr Varget and a 175 SMK.

You can tune the gas system to use slower powders, but most of them are overgassed from the factory.

Hey mathman what bullet? MB

I'm not sure how my buddy's rifle is set up.

I processed a box of R-P hulls from some factory 150 gr. Core-Lokt ammo he shot. Nothing unusual as far as the condition of the rims. I did find some variation in the head to shoulder distance.

Probably a 150 or 165 grain Interlock. He's looking to do some hog killing, not precision long range work.

An M1A level shot of 4895 under the 165 would likely do the trick.

I think Tyrone summed it up well. Stay in between the M1A and full power loads. What I find with my AR10 is you can run it close to max book loads, but its hard on primer pockets. They loosen up a bit, so watch for that. I've been shooting mine more lately and ran some loads with 4064 and pulled WWII surplus ammo 150gr fmj and I was getting groups as good as factory federal gold medal match, with zero malfunctions. Thats the thing you'll have to load for as well. The ammo has to run without malfunctioning. A double edged sword where you still want accuracy, but need reliability. If it were me, I'd use AR Comp powder, a CCI34 or BR2 primer and your 165gr hornady interlock. You can also use RL15 with excellent success. Here are some AR comp loads I was working on when I got my AR10 308. You can substitute a 165 interlock and run around the same powder charge:




I used WW brass for these loads^^


You could also run LC brass since its thicker, but thats your choice. Your R-P should work just fine. I'd also FL size the brass. I figure if I'm getting 5-8 firings out of my AR10 I'm doing good. I've got 308 brass in the tumbler right now that needs to be primed. I may try some 4895 today and let you know how it works out, but it will probably work just like any other powder I've tried in that rifle.

Brass was FL sized for smooth and reliable chambering.

Please tellll me more about that 4064/150 load. I have a fresh pound and a box or two of 150 gr. Interlocks. I used to load a lot of 4064 with 150's, but those were full snort for bolt guns.

Sounds like you are set mathman. I have some targets from thursday night and today's shooting. Instead of trying 4895, I figured I'd burn up some AA2520 and 180gr Hornady btsp interlocks. I need to burn up that AA2520 powder. It was not great in some 223 loads with 75gr Hornady match bullets. I was surprised today that I ran into some major pressure signs with that powder and the 180's, before even reaching book max loads. I had to stop shooting the AR10 after I blew a couple primers. Way too hot!!! Here are some pictures of everything from thursday and today with the AR10 308. Honest real world results. No cherry picked groups, as you can see:







Back to the drawing board, as I won't use any of these loads. They would be good enough for hunting deer at most ranges, but not real accurate.

This is just to give you an idea of how some AR10's may hit their max before book loads suggest. Just a word of caution when loading for these rifles... They aren't as bad as the M1A or winchester model 100, but you still can't load them like you would a bolt action. At least I've found I can't load my AR10 as hot as you would a bolt action.. Hope that helps.

Was thinking about a 358 barrel from Wilson Combat for my R25. Looks like fun for feral pigs and whitetail. Be Well, Rustyzipper.

Wilson combat makes some accurate barrels rustyzipper. You would probably be happy with the end result.

I just got the Nephews AR10 to do some loading for it. Its Armalite, barrel marked 11.25 twist and it has a recoil spring that feels like it could hold up a truck... Is this normal for this rifle?? I'd hate to have to clear it in the prone or in a hurry, really stiff. Are the ARs you guys have this strong??

i have 155 palmas and 2520 and 3031 that will be used up in this run of loads, plinkers and teaching his sons to get up to speed with the rifle. I load the 3031 at 39grs for the 7.62 Garand and will try the 2520 to see what the hot temps here will allow me to shoot. Gilded accuracy isnt to important yet, just function and safe pressures. I know 3031 isnt high on the go to powders, but I have butte load of it to use.

The recoil spring on the Armalite AR10 is pretty stiff. Much stiffer than your run of the mill AR15. Like you, I'll use what I have on hand as far as powder is concerned when we are talking plinking/training loads. I'll also use what bullets I have on hand that I'd otherwise not be using. These are bullets I've found over the years for real cheap, or like those 150gr FMJ pulled bullets from WWII surplus M2 ball ammo I had laying around. As far as 3031 powder is concerned, just make sure you use your bullet manufactures load data and you should be good to go. I've heard of some guys maxing out around 39.5gr of 3031 with 168gr match bullets while using LC brass. If you use WW, R-P or other commercial brass, you should be able to safely add a grain to that max, but I'd always work up to that and see where max is in your rifle. I found out yesterday with mine and using 2520. If I were going to test that powder again, I'd start a couple grains lower and then work up from there. I'd also shoot it over a chrono and watch ejection patterns. You know if your charge weight is too low because you may run into some cycling problems. Too hot and you'll see your typical marks on the case head. Way too hot and you'll start getting blown primers. Not good, as you don't want to damage you or your rifle with a blown primer...Good luck with your loading. I know mathman knows what he is doing when it comes to loading the 308win. He has far more experience with it than I do, but I figured I'd throw out some issues I ran into yesterday with the loads I ran... It may be helpful to others loading for an AR10 308 as well.. I'd also like to add that there are some great videos on youtube regarding loading for the AR10 308. One in particular I like to watch is Johnny's reloading bench. He spends an awful lot of time monkeying around with his adjustable gas block though. One thing I can say about my Armalite is it functions damned near flawlessly, without all that monkeying around with a gas block. YMMV though. Here's a video to watch. Honest groups and realtime targets with good explanation of the loads he's using:

I'd check and see if your lot of 2520 is subject to recall.

Its way too old