Bolt And Trigger Housing Assemblies

The bolt and trigger housing assemblies are complex assemblies and should not be disassembled except by the factory or qualified gunsmith.

Clean as complete assemblies with gun solvent and lightly lubricate with gun oil.


Place the receiver with the trigger housing opening upward on a clean surface.

Check to be certain that the safety button on the top rear of the receiver is fully rearward in the "ON" (SAFE) position (Fig. 2). Slide the forearm assembly onto the magazine tube while guiding the action slide bars into the corresponding cuts in the front of the receiver (Fig. 12).

Mossberg 500 Trigger Assembly Diagram

Assemble the elevator by squeezing the arms together sufficiently to position them in the receiver so that the buttons on the elevator fit into the corresponding (1/4" [6.4 mm]) diameter holes in the receiver (Fig. 11).

Pivot the elevator so that the forward portion of the elevator is even with the outside edge of the cavity in the receiver.

Insert the rear of the bolt assembly, with its bolt lock downwards toward the front inside top of the receiver, into the barrel opening of the receiver. Depress the ejector (located in the side of the receiver opposite the ejection port) to allow the bolt assembly to slide fully rearward into the receiver.

The ejector must fit into the corresponding slot in the bolt (Fig. 11).

Push the elevator down until it rests against the bolt. Position the rear of the bolt assembly even with the rear of the clearance cuts in the sides of the receiver (Fig. 13-B).

Position action bars so the notch on the bar is even with the cuts on the inside receiver walls (Fig. 13-A).

The bolt slide should be positioned with the slotted side facing up, with notch to the rear (Fig. 13).

Assemble the bolt slide, lowering the front of the bolt slide first. The bolt slide protrusion fits into the corresponding cut on the bottom of the bolt lock and action bar slots (Fig. 13-C).

Hold the bolt slide down and pull the forearm assembly forward. The bolt and bolt slide should move freely in their cuts in the receiver. If parts do not slide easily - DO NOT FORCE -disassemble and reassemble, paying attention to the relationship of the bolt, bolt slide and action slide bars.

Mossberg 590 Bolt

Position the cartridge stop and cartridge interrupter in their proper places on the inside walls of the receiver (Fig. 9).

The hooks must face inward toward the center of the cavity away from the receiver walls.

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