those are sweet. ive been using basscatchers of some type on my AR15's for years. i got my first one back in the 80's. its was hard plastic only held 60 rounds of brass and was a bit of a pain to empty. the little baggy version work great and adapt to a wide variety of semi auto not just AR15
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent