Rossi's Braztech line is basically a butt-stock and firing mechanism that can accept any one of a number of barrels. 12 ga, 20 ga, 410 ga shotguns, .22LR, .22 magnum, .223, .243, .17, and maybe a few .30+ calibers. Any one of the barrels will fit on the base. Right now you buy it with 2 barrels, but they are soon to open up the shop selling you any barrel you want for your gun. Mine happens to be a 12 ga. / .22 magnum combo. The single shot 12 ga. is nice as a slug gun for deer hunting, or can make a decent bird / small game gun with the right size shot. The .22 magnum is a nice plinker and varmint round. I'm seriously thinking about adding a .223 barrel for it when they are available.