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Work order — Mossberg 500 / 590

Taking the firearm apart for a job such as refinishing, and putting it back together to specification. Generated from the Pew-Takedown entry last updated 2026-10-29. Confidence: high.

Shop difficulty: Tier 1 of 3

About 51 listed items (several are pre-assembled groups) that mostly slip in and out once the trigger housing pin is pushed; the traps are an alignment puzzle (bolt slide and action bars) and the hammer-cocked/safety-on order, not held springs. Removing the magazine tube for a bare receiver needs only a strap wrench and the forend nut a tube-nut tool. 51 parts (Generic parts list for the whole 500/505/510/535/590/835 pump family, including optional stocks and accessories; trigger housing and bolt are listed as assemblies). Pew-Takedown's rating, not the manufacturer's.

Bench time: strip ~30 min, rebuild ~45 min (estimate). Actual: strip ______ rebuild ______

Special tools:

• Tube nut tool — Forend action slide tube nut
• Strap wrench and padded vise — Magazine tube off the receiver
• Long socket extension — Stock bolt deep in the buttstock
• Roll/pin punches 1/16-1/8 in. — Bolt extractor and firing pin pins

Watch for:

• The bolt, bolt slide and both action slide bars have to go back in the same relationship they came out; a bar out of its cut or a bolt slide offered at the wrong point of forend travel will not drop in or binds the action. (reassembly; O.F. Mossberg & Sons, Inc.)
• Owners report the shell stop and interrupter get jammed in wrong and the action bars mis-seated when the gun is forced together; it only runs once everything lines up. (reassembly; Calguns.net)
• The hammer must be at full cock to get the trigger housing back in, and the safety must be on to reinstall the bolt; neither is obvious and forcing it damages parts. (reassembly; American Rifleman (NRA))
• Getting the receiver bare means unscrewing the magazine tube from the receiver, which the Army does with the receiver in a capped vise and a strap pipe wrench. (both; Headquarters, Department of the Army)
• The action slide tube nut that holds the forend on is removed and refitted with a dedicated tube nut tool. (both; Headquarters, Department of the Army)

Tools

• Punch (roughly 1/8 in) — Pushing out the trigger housing pin if tight.
• Flat-blade screwdriver or coin — Turning the takedown screw on 500-series guns.

1. Clear and make safe

Manufacturer's video: Loading and Unloading - Mossberg 500 / 590 Series Shotguns (MOSSBERG)
https://www.youtube.com/watch?v=3_ufCUSZ27s

1. Point the muzzle in a safe direction and keep your finger off the trigger.
2. Move the safety button fully rearward to the ON (safe) position.
3. Depress the action lock lever on the left side behind the trigger guard and pull the forearm rearward to open the action.
4. Cycle the action repeatedly, catching each shell as it ejects, until no more shells feed from the magazine tube.
5. With the action open, visually and physically check the chamber, the elevator, and the magazine tube.
   Warning: Three places, not two. The manual names the chamber, the elevator, and the magazine tube specifically.
6. Remove all live ammunition from the work area, and put on eye protection before going further.

2. Disassemble

Field Strip

1. Complete the Clear and Make Safe procedure and put on eye protection.
2. Depress the action lock lever and open the action by sliding the forearm fully rearward.
3. Move the forearm slowly forward from the fully rearward position until the front of the bolt sits in the middle of the ejection port.
   Warning: Do not skip this. The barrel will not come out cleanly unless the bolt is positioned here first.
   Tip: This is the step most commonly left out of informal instructions for this shotgun.
4. On a 590 or 835, unscrew the magazine cap counterclockwise. On a 500, 505, 510 or 535, loosen the takedown screw counterclockwise until its threads are completely disengaged from the end of the magazine tube.
   Warning: On 590 and 835 models the magazine spring retainer and spring are under significant spring pressure.
5. Remove the barrel from the receiver with a gentle back-and-forth rotational movement while pulling it out of the receiver assembly.
   Tip: Rotate as you pull. Pulling straight out is the common mistake.
6. Position the shotgun on a clean surface with the trigger guard upward.
7. Using a punch no greater than 3/16 in (4.76 mm) in diameter, push out the small-diameter trigger housing retainer pin from the side of the receiver, roughly 1/2 in (12.7 mm) below the rear of the trigger guard.
8. Remove the trigger housing assembly by lifting the rear portion upward first.
   Warning: Once the trigger housing is out of the receiver, do not pull the trigger and let the hammer fall. The manual warns this can injure you and damage the assembly.

Disassembly of Internal Receiver Components

1. Complete the field strip, with the trigger housing assembly removed.
   Warning: Before going further, study how the internal components are arranged inside the receiver. The manual asks for this explicitly.
2. Remove the cartridge interrupter and cartridge stop from the receiver.
   Tip: It may be necessary to tap the sides of the receiver lightly to release these parts. On left-hand models they sit in the same positions but the ejection port is on the opposite side.
3. Move the forearm and action slide assembly rearward until the bolt assembly and bolt slide are three quarters of the way rearward.
   Warning: Pay attention to the position of the bolt, bolt slide, and action slide bar assembly — they must be in the same relationship on reassembly.
4. When the bottom of the bolt slide aligns with the clearance cuts in the sides of the receiver, lift the bolt slide upward and out of the receiver.
5. Remove the bolt assembly by sliding it forward and out of the receiver through the barrel opening at the front.
6. With the safety button fully rearward in the ON position, pivot the front portion of the elevator upward out of the receiver and squeeze its arms together to free it.
   Warning: The safety must be fully rearward in the ON position for the elevator assembly to come out.

Disassemble the fore end assembly

1. Remove the barrel and take the fore end assembly off the receiver (operator field strip, WP 0014 00).
2. Unscrew the slide tube nut from the action slide assembly with the tube nut tool.
   Tip: The tube nut tool is a manufactured item; WP 0030 00, Figure 1 gives its dimensions (1080 bar stock).
3. Remove the slide grip and the anti-rattle spring from the action slide assembly.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.

Strip the barrel assembly (heat shield, front sight, sling swivel)

1. Field strip the shotgun and remove the barrel (WP 0014 00).
2. On the Model 590, remove the two self-locking nuts, the two screws, the heat shield spacer and the heat shield from the barrel.
   Tip: Discard the self-locking nuts; new ones are used on assembly.
3. Remove the front sight from the barrel.
4. On the Model 500, remove the retaining ring and the machine screw from the barrel.
5. Remove the sling swivel only if it is damaged. On an old-style swivel, remove the screw, the swivel and the sleeve bushing.
6. On a new-style swivel, turn the locking knob fully counterclockwise.
   Tip: Removal of the old and new swivel is the same for both models.
7. Push in on the locking knob to release the swivel-locking bar and remove the sling swivel from the swivel post.
8. Turn the swivel post counterclockwise to remove it.

Remove the buttstock and recoil pad

1. Remove the two machine screws and the recoil pad from the stock.
2. Remove the machine screw, washer and lock-washer from inside the stock.
   Tip: Discard the lock-washer; a new one (P/N 7615P) is used on assembly.
3. Separate the stock from the receiver.
4. Remove the sling swivel only if it is damaged. On an old-style swivel, remove the screw and the swivel, and on the Model 500 also the sleeve bushing and swivel washer.
5. On a new-style swivel, turn the locking knob fully counterclockwise, push it in to release the swivel-locking bar, and remove the sling swivel from the swivel post.
6. Turn the swivel post counterclockwise to remove it.

Remove the pistol grip assembly

1. Field strip the shotgun (WP 0014 00).
2. Remove the hex screw, washer and lock-washer from the pistol grip.
   Tip: Discard the lock-washer; a new one (P/N 7613P) is used on assembly.
3. Remove the swivel post.

Remove the magazine spring, follower and magazine tube

1. Remove the barrel assembly and the fore end assembly (WP 0014 00).
2. Model 590: remove the magazine catch retainer, the magazine spring and the cartridge follower from the magazine tube.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
3. Wrap a wiping rag around the receiver and clamp it in a bench vise with jaw caps, closing the vise just enough to hold it.
   Tip: On the Model 590 do this and the next two steps only if the magazine tube must be replaced. On the Model 500 they come first, because the follower and spring come out after the tube is off.
4. Place a strap-style pipe wrench around the magazine tube and turn it to the left (counterclockwise) to loosen it.
5. Remove the magazine tube from the receiver.
6. Model 500: remove the cartridge follower and the magazine spring from the magazine tube.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.

Disassemble the bolt assembly

1. Field strip the shotgun and remove the bolt (WP 0014 00).
2. Remove the grooved headless pin and the bolt lock from the bolt.
3. Remove the two cartridge extractor pins, the left-hand and right-hand cartridge extractors, and the two extractor springs from the bolt.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
4. Remove the firing pin retaining pin, the firing pin, the flat washer and the spring from the bolt.
   Tip: WP 0029 00 calls this spring the 'follower spring'; the parts list (WP 0040 00, item 9) names it SPRING, FIRING PIN.

3. Refinish

The components the procedures above separate. Coating, masking and cure are outside this database; follow your coating system's instructions. A part the manufacturer marks "factory fit" should not be swapped or reworked.

No manufacturer statement of materials or finish is recorded. Identify each part's material before choosing prep and cure.

4. Reassemble

Disassemble the bolt assembly

1. Reverse the steps of "Disassemble the bolt assembly".

Remove the magazine spring, follower and magazine tube

1. Reverse the steps of "Remove the magazine spring, follower and magazine tube".

Remove the pistol grip assembly

1. Reverse the steps of "Remove the pistol grip assembly".

Remove the buttstock and recoil pad

1. Reverse the steps of "Remove the buttstock and recoil pad".

Strip the barrel assembly (heat shield, front sight, sling swivel)

1. Reverse the steps of "Strip the barrel assembly (heat shield, front sight, sling swivel)".

Disassemble the fore end assembly

1. Reverse the steps of "Disassemble the fore end assembly".

Disassembly of Internal Receiver Components

1. Reverse the steps of "Disassembly of Internal Receiver Components".

Reassemble the fore end assembly

1. Slide the slide grip onto the action slide assembly.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
2. Install the anti-rattle spring.
3. Screw the slide tube nut onto the action slide assembly and tighten it with the tube nut tool.

Reassemble the barrel assembly

1. Install the swivel post by turning it clockwise.
   Tip: If an old-style swivel was removed, replace it with the new-style swivel.
2. Turn the locking knob fully counterclockwise.
3. Push in on the locking knob to release the swivel-locking bar and insert the bar through the swivel post.
4. Tighten the locking knob by turning it fully clockwise.
5. Install the front sight on the barrel.
6. On the Model 590, install the heat shield, the heat shield spacer, the two screws and two new self-locking nuts on the barrel.
7. On the Model 500, install the retaining ring and the machine screw on the barrel.

Install the buttstock and recoil pad

1. Install the swivel post by turning it clockwise.
   Tip: If an old-style swivel was removed, replace it with the new-style swivel.
2. Turn the locking knob fully counterclockwise, push it in to release the swivel-locking bar, and insert the bar through the swivel post.
3. Tighten the locking knob by turning it fully clockwise.
4. Align the stock with the receiver assembly.
5. Place the washer and a new lock-washer on the shaft of the machine screw.
6. Insert the machine screw into the end of the stock and tighten it into the receiver.
7. Align the recoil pad with the end of the stock and secure it with the two machine screws.

Install the pistol grip assembly

1. Align the pistol grip to the receiver.
2. Place a new lock-washer and the washer on the hex screw and insert it into the pistol grip.
3. Tighten the hex screw hand tight only.
4. Install the swivel post.

Install the magazine tube, spring and follower

1. Model 500: insert the magazine spring and the cartridge follower into the magazine tube.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
2. Wrap a wiping rag around the receiver and clamp it in a bench vise with jaw caps, closing the vise just enough to hold it.
   Tip: On the Model 590, do this and the next step only if the magazine tube was replaced.
3. Place a strap-style pipe wrench around the magazine tube and turn it to the right (clockwise) to tighten it.
4. Model 590: insert the cartridge follower, the magazine spring and the magazine catch retainer into the magazine tube.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
5. Assemble the weapon (WP 0014 00) and perform a function check.
   Tip: WP 0028 00 ends with: after any work, check the shotgun for proper functioning before firing live ammunition.

Reassemble the bolt assembly

1. Install the firing pin spring, the flat washer, the firing pin and the firing pin retaining pin in the bolt.
2. Install the two cartridge extractor springs, the right-hand and left-hand cartridge extractors, and the two cartridge extractor pins in the bolt.
   Warning: To avoid injury to your eyes, use care when removing and installing spring-loaded parts.
3. Install the bolt lock and the grooved headless pin in the bolt.

Reassembly

1. Confirm the safety button on the top rear of the receiver is fully rearward in the ON position, and place the receiver with the trigger housing opening upward on a clean surface.
2. Slide the forearm assembly onto the magazine tube, guiding the action slide bars into the corresponding cuts in the front of the receiver.
   Warning: Both action slide bars must enter their cuts. One out of its track will bind the action.
3. Squeeze the elevator arms together enough to position them in the receiver so the studs on the elevator fit into the corresponding 1/4 in (6.4 mm) holes, then pivot the elevator so its forward portion is even with the outside edge of the receiver cavity.
   Tip: Only needed if the elevator was removed.
4. Insert the rear of the bolt assembly into the barrel opening of the receiver, with its bolt lock downward toward the front inside top of the receiver, and depress the ejector on the side of the receiver opposite the ejection port so the bolt can slide fully rearward.
   Warning: The ejector must fit into the corresponding slot in the bolt.
5. Position the action slide bars so the notch on the bar is even with the cuts on the inside receiver walls, push the elevator down until it rests against the bolt, and position the rear of the bolt assembly even with the rear of the clearance cuts.
6. With the bolt slide slotted side up and its notch to the rear, assemble the bolt slide by lowering its front first, so its protrusion fits the cut on the bottom of the bolt lock and its two side protrusions fit into each action slide bar slot.
7. Position the cartridge stop and cartridge interrupter in their places on the inside walls of the receiver, with the hooks facing inward toward the centre of the cavity and away from the receiver walls.
8. Cock the hammer, then set the trigger housing assembly into the receiver and insert its retainer pin.
   Warning: The hammer must be fully cocked or the trigger housing will not go into the receiver. Do not force it.
9. Set the barrel into the receiver with a gentle rotational movement, seating the barrel extension fully with the barrel ring over the magazine tube.
10. Install and tighten the takedown screw (500 series) or magazine cap (590 and 835) firmly by hand.
    Warning: A loose barrel retainer lets the barrel move under recoil. Check it before every use.
11. Perform the function check.

5. Torque

Reported by other sources — not the manufacturer

Fit or check on rebuild

• Magazine tube torqued and aligned to the barrel lug — Tube carries the barrel; it is refitted hand-tight-plus with a strap wrench and must line up with the takedown screw or cap.
• Safety detent feel — The tang safety's ball and spring under the detent plate set the click; a missing ball gives a loose safety.
• Function check: safety, trigger/sear release, disconnector and feeding with dummy rounds — Standard after any detail strip; a mis-assembled sear or disconnector can double or fail to fire.

6. Function check

• After any cleaning, disassembly, or accessory installation, check the shotgun for proper functioning before firing live ammunition.
• Move the safety button fully rearward to the ON position and keep the muzzle pointed in a safe direction.
• Open the action and visually and physically check the chamber, elevator, and magazine tube to be certain the shotgun is unloaded.
• Depress and hold the action lock lever, then open and close the action several times to check for free movement.
• Close the action, leave the safety ON, and pull the trigger fully rearward. The hammer should not fall.
• Remove your finger from the trigger and move the safety button to the OFF (fire) position. The hammer should not fall.
• With the safety OFF, pull the trigger. The hammer should fall.
• Load two dummy shells into the magazine and confirm they feed and eject cleanly, one per cycle.
• Confirm the takedown screw or magazine cap is tight.

If any check fails, the firearm is not safe to fire. Stop and see a licensed gunsmith.

Sources

1. Owner's Manual for 500, 505, 510, 535, 590 and 835 Pump Action Shotguns — O.F. Mossberg & Sons, Inc. primary
   https://resources.mossberg.com/hubfs/manuals/12173-Owners-Manual-Pumps-English.pdf
2. Mossberg 590 / Remington 970 Stock - MI-SG-590 / MI-SG-870 installation instructions — Midwest Industries, Inc. secondary
   https://midwestindustriesinc.com/content/installation-instructions/Mossberg-590-Remington-970-Stocks-Instructionrs.pdf
3. TM 9-1005-338-13&P: Technical Manual, Unit and Direct Support Maintenance (including Repair Parts and Special Tools List) for Mossberg 12-Gauge Shotgun, Model 500 (1005-01-295-1832) and Mossberg 12-Gauge Shotgun, Model 590 (1005-01-251-8578) — Headquarters, Department of the Army primary
   https://archive.org/download/16-manuali-duso-e-manutenzione-per-armi-specifiche-use-and-maintenance-manuals-f_20230430/ARMY%20TM%209-1005-338-13%26P%20Technical%20Manual%20for%20Mossberg%2012-Gauge%20Shotgun%20Model%20500%2C%20590%20-%20May%202005.pdf
4. Magpul MAG508 Forward Sling Mount – Remington 870 & Mossberg 500/590 — Installation Instructions — Magpul Industries secondary
   https://magpul.com/media/wysiwyg/Instructions/MAG508_SGA_Forward_Sling_Mount_Rem_Moss_INSRT.pdf
5. Mesa Tactical Telescoping Stock & Adapter Shotgun Conversion Kit — Assembly Guide (#47371 Rev II) — Mesa Tactical secondary
   https://mesatactical.com/content/manuals/47371_Stock_Adapter_Manual_rev_ii.pdf
6. Mesa Tactical SureShell Shotshell Carriers — Assembly and Operation Guide (47374) — Mesa Tactical secondary
   https://mesatactical.com/content/manuals/47374_SureShell_Shotshell_Carriers_Assembly_and_Operation_Guide.pdf
7. XS Sights Banded Shotgun Front Sight / Winged Ghost Ring — Installation Instructions — XS Sights secondary
   https://xssights.com/content/Install%20Instructions/Banded%20Shotgun%20Winged%20Ghost%20Ring%20Instructions.pdf
8. XS Sights SHOTRAIL (Remington/Mossberg) with Banded Front Sight — Installation Instructions — XS Sights secondary
   https://xssights.com/content/Install%20Instructions/SHOTRAIL%20Banded%20Front.pdf
9. Seeking help from someone who owns a Mossberg 500 in the Bay Area — Calguns.net anecdotal
   https://www.calguns.net/forum/general-discussion/general-gun-discussions/910351-seeking-help-someone-own-mossberg-500-in-bay-area?p=21089362
10. The Mossberg Model 500: History & Disassembly — American Rifleman (NRA) secondary
    https://www.americanrifleman.org/content/the-mossberg-model-500-history-disassembly

Educational guide only. Some information comes from non-authoritative sources. Always consult your manufacturer's manual and a licensed gunsmith. Verify your firearm is unloaded before every procedure. Full disclaimer: https://github.com/Fundamental-build-LLC/Pew-Takedown

Legal notice: this material is third-party information compiled from sources of varying reliability and is provided for general informational and educational purposes only. It is not gunsmithing, technical, safety or legal advice, it is not verified or endorsed by any manufacturer, and it must not be taken as fact. Any work on a firearm beyond the routine field stripping described in its own owner's manual should be performed only by a licensed and insured gunsmith. You use this material entirely at your own risk. Fundamental Build LLC and the project's contributors make no warranty of any kind and accept no liability for death, injury, damage or loss arising from its use. Full terms: LEGAL.md.