Colt H2 Buffer Colt H-Series buffers are an excellent reliability upgrade shooters can make to their AR-15 carbines. Heavy buffers can reduce felt recoil as well as reduce the cyclic rate on full-auto and AR-15 Semi automatic rifles. Standard carbine buffers contain three steel weights, the H buffer has two steel weights and one made from heavier tungsten. The H2 has two tungsten weights and one steel.