I'd like to get a bolt carrier with more mass on the rear of the carrier. I really want the DPMS M16 carrier. What would I need to do to get one (besides the obvious answer of ordering it)? It will be installed in a semi-auto rifle. As far as I've heard, it's legal to have the M16 carrier in a semi-auto rifle, so long as it doesn't function in full auto. Somehow the extra mass in the rear makes it "easier" to convert, but I don't see how. I just want the extra mass for recoil damping.