A shell feeding system for a top loading shotgun in one embodiment includes a barrel, receiver, and a magazine. The magazine includes a cavity configured to receive a plurality of ammunition shells in stacked end-to-end relationship. The magazine is positioned above the barrel and extends forward from the receiver. A load gating and locking block engages and guide each shell in a feed pathway towards the lower part of the receiver for chambering. In one embodiment, the receiver and magazine may be formed as a unitary integral structure forming a single piece.