go to 1:30 and watch
I've heard about using a sling on a stockless "handgun" as a stabilizing technique, and I've done it before with a pap92 via a single point sling that was bungee basically, it works ok
never thought about doing what these guys are doing. it probably works......but that **** looks like it would hurt my neck lol
also, I dont know how I feel about moving around with a sling around my neck