Disassembly of internal receiver components

CAUTION: Pay special attention to the position of the bolt, bolt slide and action slide bar assembly during this portion of the disassembly, as the parts must be in the same relationship during reassembly.

Remove the cartridge interrupter from the ejection port side and cartridge stop from the opposite side. (It may be necessary to tap the sides of the receiver lightly to release these parts) (Fig. 9).

Mossberg 500 Disassembly

Move the forearm/action slide assembly rearward so that the bolt assembly and bolt slide are three quarters of the way rearward. When the bottom of the bolt slide is aligned with the clearance cuts in the sides of the receiver, lift the bolt slide upward and out of the receiver (Fig. 10).

Remove the bolt assembly by sliding it forward and out of the receiver assembly through the barrel opening at the front of the receiver (Fig. 11-A).

NOTE: The safety button located on the upper rear of the receiver must be fully rearward in the "ON" (SAFE) position to remove the elevator assembly (Fig.2).

Pivot the front portion of the elevator upward out of the receiver (Fig. 11-B). Squeeze the two arms which form the open end of the elevator assembly together sufficiently to disengage and remove the elevator from the receiver (Fig. 11-C).

Mossberg 835 Disassembly
Fig. 11 — Elevator removal Remove the forearm/action slide assembly by sliding it forward and off the magazine tube.

A CAUTION: Field disassembly is now complete! The shotgun should not be disassembled further for routine cleaning or maintenance. Further disassembly should only be performed at the factory or by a qualified gunsmith.


With proper maintenance and care, your Mossberg® firearm will provide you with years of dependable service. Your firearm should be inspected and cleaned periodically to ensure that it remains in good condition. Clean your firearm as soon as possible after use. This is especially important if your firearm has been exposed to moisture. For maximum performance and continued satisfaction with your firearm, periodic cleaning and lubrication are essential.

Follow the instructions and equipment provided with a quality gun cleaning kit.

A Always be sure that the safety button is fully rearward in the "ON" (SAFE) position (Figure 1) and that the firearm is unloaded by visually and physically checking the chamber, elevator, and magazine tube before cleaning your firearm. Wear eye protection during cleaning.

Normal use requires only that the mechanisms be free of excessive shooting residue. Very little lubrication other than a light oiling of internal and external surfaces to prevent rust is needed.

To ensure optimum performance, Mossberg recommends thorough cleaning of your firearm after every 200 rounds. However, unusually dusty, dirty, or harsh weather conditions, or use of ammunition which leaves significant powder residue may require more frequent cleaning.

If the firearm is to be stored for a long period of time, it should be thoroughly cleaned and oiled. Do not plug the barrel or store in a fabric-lined case that will absorb lubricant from the firearm, as this may result in corrosion to the unprotected metal surfaces.

Over-lubrication should be avoided during below freezing conditions. Many lubricants thicken in low temperatures which could affect the operation of the firearm. Exposure to unfavorable weather or moisture from condensation requires additional care to prevent corrosion to the firearm.


Scrub bore and chamber with solvent and follow with cleaning patches until barrel is clean. A final pass with a lightly oiled patch will provide a protective coating. A stiff brass bristle brush is useful for removing stubborn deposits.

Be sure not to leave cleaning patches or excessive oil or grease in the bore as they can create dangerous obstructions. Obstructions of any kind can cause damage to the firearm and may result in serious personal injury to the shooter and/or others nearby.


Clean all components of the action including the bolt, bolt slide and action slide bars (Figure 11) to remove accumulated residue. An evaporating solvent should be used. Action parts will remain cleaner longer if lubrication is used sparingly.


Clean the inside of receiver with a rag or soft brush, giving special attention to the tracks which guide the bolt and bolt slide. Place a few drops of light oil in these tracks when clean. Care should be taken when cleaning the exterior surfaces of the receiver to prevent cosmetic damage. Never use a brush with metal bristles, as this could remove the protective coating on the receiver.


Brush loose residue from trigger housing with a soft bristle brush. Never use a brush with metal bristles, as this could remove the protective coating on the trigger housing.

A Never pull the trigger while the trigger housing is removed from the receiver, as damage to the trigger housing and/or personal injury may result.


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).

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).



Fig. 12



Fig. 12

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 500 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. TRIGGER HOUSING ASSEMBLY INSTALLATION

NOTE: Hammer must be in the fully-cocked position to allow the trigger housing to be inserted in the receiver.

Hold the cartridge stop and cartridge interrupter in place firmly against the receiver walls with one hand and grasp the trigger housing assembly with the other (Fig. 9).

Insert the lugs on each side of the front corner of the trigger housing into the slots on each side of the receiver (Fig. 14-A), then ease the rear of the housing assembly down and into position (Fig. 14-B). DO NOT FORCE!

NOTE: If the trigger housing does not fit into place easily, check that all internal trigger housing pins are flush with the side of the housing and that the cartridge interrupter and cartridge stop are positioned properly.

Align the trigger pin hole in the housing assembly with those in the receiver. Insert the trigger housing pin and push in fully until flush with the side of the receiver (Fig. 14).

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