[Manuel_D]

Commerical Nerf guns don't even hold a candle to the DIY builds. The easiest type is a muzzle loader that accelerates a weight into a piston. A more advanced one has a rotating drum of muzzles advanced and fired by compressed air.

Apparently these days it's possible build magazine fed nerf guns but most designs require a different sort of Nerf projectile where the suction cap is a smaller diameter than the foam body - otherwise there's no easy way to build a feed system. Back when I was a kid we only had the traditional style.