I'd eventually like to get a .300 Blackout upper and shoot cast lead 240gr. bullets out of it. That would be fun, inexpensive to shoot, and considerably less noisy than 5.56mm. I've got a 11.5" upper now in 5.56mm but I truly loathe the noise. I don't think I'll shoot it again without first replacing the A2 flash hider with a Noveske Pig or the DLASK copycat. Anything to re-direct all that muzzle blast is a good thing in my mind.