I've spent a large chunk of my life on the M16 platform, which is why i won't move off to anything else.
Seen my dad (two wars with the M16) keep squeezing the trigger on an 870 (which he's also carried during the Gulf War, but never ended up firing) during a match till it clicked that he was not firing an M16, and remembered to pump. That split second hesistation happened on every shot for the first string, after that, it kicked back in and he remembered what to do.
He hasn't carried a 1911 in nearly 20 years, but carried one from 1966-1991 in the military. His hands remember what to do, even when his brain occasionally forgets.
"And Shepherds we shall be. For thee, my Lord for thee. Power hath descended forth from thy hand, that our feet may swiftly carry out thy command. So we shall flow a river forth to thee and teeming with souls shall it ever be. In nomine Patris, et fili, et Spiritus Sancti. Amen."