Gee, guys. I learned a whole lot of stuff I had no clue about before this morning.
Such as, machineguns have "rifled chambers" because the round fires before the bolt closes and locks. Evidenced by existance of fired cases with "rifling marks". He didn't want to hear about H&Ks striated chambers and their purpose, though.
A relatively small suppressor (approx 12-15 inches by 1.5 dia.) will completely silence a heavy caliber centerfire rifle.
He also mentioned a "freezeplug suppressor" which I've never heard of, but I can at least make sense of the concept.
The best one was, "an M16 fires with an open bolt" and fires before the bolt lugs engage, and m16 bolts and AR 15 bolts are different but interchangeable.
(Not bolt carriers, bolts), I asked to be sure I understood him.
There was a fair bit of other derp, but I'm sure you get the idea.
Is there some video game where these people "learn" this stuff or what?