I quit learning about those things when I turned my -16A1 in a long time ago. Thing that puzzles me these days is the fascination with short barrels. Velocity God smiles if you add another 4” of barrel and your ears might benefit a bit as well.

I am..........disturbed.

Concerning the difference between man and the jackass: some observers hold that there isn't any. But this wrongs the jackass. -Twain