Yes the old m-16's have a spring in the barrel, ask anyone thats shot them in the prone position the fucking thing goes TWANG in your ear after every shot. As for the 12 ga, our shotguns are a catch 22 great stopping power but i havent see anyone shoot them and not have blood splotes under their skin the next day. The 14" barrel gives a HUGE kick. The funny thing is as soon as your done shooting the course they reload you w/ less than leathal ammo and run you through the same course of fire again. Only problem is the fucking thing kicks like a daisy air rifle. I love to watch new people shoot it cause you see them tense up and throw themselves into the gun anticipateing the shot then its like pfft. Everyone laughs, plus you can tell who's anticipateing the shot!!!!!