I have an Adams Arms Piston conversion kit on my RRA, and a friend of mine recently acquired a pair of Magpul BUIS of the Gen 2 verity. Now I remember seeing on the Magpul website not to use their sights on gas blocks due to the possibility of melting... BUT would this also apply to piston kits, or even especially to pistons due to the gas or would that negate the concerns? He offered me the sights but if I cant use them I'd rather let him keep them. I would think that because its not the lowest quality polymer and its only a semi auto that it wouldn't have problems. That and the gas all exhausts out in all directions from the piston.