So I am dumb regards this, I have H2 buffers in one carbine gas and one mid gas, both mil spec buffer tubes, both collapsable stocks, both purchased complete from factory, both work with everything and all the time. I bought an LMT defender 2000 lower with an H3 buffer thinking to use it if I built a 300blackout, I sold it recently because I lost interest in that idea. So it probably will not work with 5.56??? I better call the guy and tell him.
