wacking m16 mags on your helmet?

[Death from Afar]

I have always down this with my issue Steyr. I am not sure why this is, a loaded mag is under such tension I doubt you would move the rounds very far at all unless you were willing to give your self concussion. I always did it to knock the lint, sand and other junk off the top cartridge. And it looks cool, which is 90% of soldiering,

 

[38splfan]

Sand

I used to do it against my kneepad or thigh.

I was really more concerned about sand in the mag than seating. I generally repacked my mags every day or two, and was pretty particular about the way I loaded the rounds.

Surgical gloves covered mags for daily duty, and came off for missions/guard/convoys.