rear of barrel(n = noun.artifact) breech, rear of tube - opening in the rear of the barrel of a gun where bullets can be loaded;
is a kind of opening
is a part of barrel, cask
has parts: breech closer, breechblock

barrel, barrel cactus, barrel knot, barrel maker, barrel organ, barrel process, barrel roll, barrel vault, beer barrel, golden barrel cactus, gun barrel, pickle barrel, pork barrel, rain barrel, rear, rear admiral, rear back, rear end, rear lamp, rear light, rear of tube, rear window, trash barrel, wine barrel