All of you non military veterans would shit if I told you how many times I've seen soldiers rest their chin on the muzzle of an m4 or m16 in my 25 year career. Not saying the behavior is "ok"......just stating that it's common practice in the army.....very common.
This.
Every time I read a thread here about irate NESers getting "swept," I think about walking around on infantry patrols and remember that I got "swept" about 40,652 times per minute.
It's why you keep your booger hook off that bang swich.