From my experience in reloading for my M1 Garand, and also for the M14 Match rifle that I shot with the Marines, I've learned a few things. First off, standard chambers such as the type that you'd find on factory or Military surplus weapons tend to be right near the middle of the industry standard if not a tad looser on the military side. Tighter chambers are possible, but as a rule, they are near standard. This means that the ammo that you load with Std dies should feed with out any hitches. If your AR10 has a match chamber (as my M14 did) then you might run into some chambering and locking problems. A set of Small Base sizing dies would help in this case, as the SB dies size the cases down to the absolute minimum specs, and were designed with autoloaders in mind. The only problem (as I hear it) is that the SB dies work the brass so much, that case life is reduced from normal. I haven't seen this though. The military stuff we "reloaded" was "Mexican Match" and we only reloaded the cases once. My Garand likes what ever I feed her, so I've yet to use the SB dies with her. Bolt actions, with the powerful camming action of the closing bolt, are a bit more forgiving then autoloaders are as far as reloads go. Ammo which chambers and fires in the trusty old Bolt gun might not allow the bolt to go completely home with your AR10. Does the AR10 have a Forward assist? Not that this would help much, just curious. Small Base dies are available from RCBS in a set, or just the sizer. MidwayUSA sell them both ways. Try the normal loading dies, and if there are problems, look into the SB dies. As far as loads go, I'd suggest asking Armalite, and I'd hesitate at telling you what my pet load was because I don't know anything about the strength of that action. Good luck and hold the Ten ring!