Buying used means that the rifle you've been eyeing is suddenly affordable. You can become the proud owner of a .223, .243, or .270 caliber Winchester rifle. from any era. Gander Mountain's selection of used guns includes 12 gauge shotguns like a Mossberg 500 or a .300 Winchester Magnum Shotgun, and even 20-gauge beginner's shotguns for kids. And where else can you find a quality Colt AR-15 for cheap?