Functional? Are you kidding me? The Glock 9mm version accepts 33 round G18 mags, that long barrel maximizes the 9mm cartridges energy potential. Trust me, send a few hot jacketed hollow points down range and you’ll see how functional it is. Its much easier to hit something with a carbine rather than a pistol. Reliabilty with this gun is very good according to many owners who actually fire the gun regularly. Its very simple and rugged based on a blowback design.