I wouldn't be too concerned with what DPMS uses versus what will work "best" for you. Most DPMS factory guns are already overgassed. Combine a RLGS, along with overgassing, a carbine-length extension/buffer/stock, along with a lightweight basic 3oz CAR buffer, and the rifle probably isn't cycling as ideally as it otherwise could. If you are building, I'd opt for a heavier buffer were I in your shoes (like an H2 or ST-T2), but YMMV depending on what ammo you'll be running, the conditions you'll be running the rifle in, etc.
