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Work order — Mossberg 590 Shockwave

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: medium.

Shop difficulty: Tier 1 of 3

The shortest list in the category (34 items) on the 500/590 action; nothing held under tension while a pin goes in. Same alignment traps as the 500 (bolt slide and action bars, shell stop and interrupter) and the 590 magazine spring retainer. 34 parts (Shockwave exploded-view parts list shared by the 500 and 590 Shockwave (rows 1 and 4 are 500-only, 7 and 8 are 590-only); trigger housing and bolt 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.)
• On 590-pattern guns the magazine spring retainer and spring are under significant pressure when the cap comes off or goes back on. (both; 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))

Tools

• Punch (roughly 1/8 in) — Pushing out the trigger housing pin if tight.

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. Push the tang safety rearward to the safe position.
3. Press the action lock lever and pull the forend rearward to open the action, keeping your support hand behind the strap.
4. Cycle the action repeatedly, catching each shell, until no more feed from the magazine tube.
5. With the action open, inspect the chamber and look up the magazine tube with a light.
   Warning: The chamber AND the tube.
6. Physically confirm the chamber is empty and remove all live ammunition from the work area.

2. Disassemble

Field Strip

1. Complete the Clear and Make Safe procedure.
2. Close the action and unscrew the magazine cap at the muzzle end of the magazine tube.
3. Pull the barrel straight forward and off the magazine tube.
4. Push out the trigger housing pin from the left side of the receiver.
5. Lift the trigger housing assembly down and out of the receiver.
6. Slide the forend assembly forward and withdraw the bolt and bolt slide out the front of the receiver.
   Warning: Do not bend the cartridge stops.

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.

The manufacturer's full parts list (34 parts) is on the reference page.

4. Reassemble

Reassembly

1. Set the bolt slide into the bolt and feed the assembly into the receiver, both action bars in their grooves.
2. Slide the forend rearward until the bolt is fully in the receiver.
   Warning: One bar out of its track will bind the action.
3. Install the trigger housing and its pin.
4. Seat the barrel fully into the receiver.
5. Install and hand-tighten the magazine cap firmly.
   Warning: Check it before every use.
6. Cycle the action several times and perform the function check.

5. Torque

No manufacturer torque values are recorded for this firearm.

Notes: The manufacturer's documents give no torque value. They say: "With a 1/4” allen head wrench attach the Raptor Grip to the receiver by tightening the socket head cap screw as seen in Figure 28." (Owners Manual for 500 and 590 Shockwave and Compact Cruiser (doc 103855), PDF p. 19) "Slide the barrel into the receiver and tighten the magazine cap, finger tight only. DO NOT use pliers or a wrench to tighten magazine cap." (Owners Manual for 500 and 590 Shockwave and Compact Cruiser (doc 103855), PDF p. 7)

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

• Verify the shotgun is unloaded — chamber and magazine tube — before each step.
• Cycle the action fully and confirm it locks closed.
• With the hammer cocked, engage the safety and press the trigger. The hammer must not fall.
• Disengage the safety and press the trigger. The hammer should fall.
• With the hammer down, confirm the action will not open until the action release is pressed.
• Load two dummy shells into the magazine and confirm they feed and eject one at a time.
• Confirm the forend strap is intact and secure — it is what keeps your hand behind the muzzle.

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

Sources

1. Mossberg 590 Shockwave Owner’s Manual — O.F. Mossberg & Sons, Inc. primary
2. Owners Manual for 500 and 590 Shockwave and Compact Cruiser (doc 103855) — O.F. Mossberg & Sons, Inc. primary
   https://resources.mossberg.com/hubfs/manuals/103855-Pump-Action-Firearms-002.pdf
3. 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
4. The Mossberg Model 500: History & Disassembly — American Rifleman (NRA) secondary
   https://www.americanrifleman.org/content/the-mossberg-model-500-history-disassembly
5. TM 9-1005-338-13&P — 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

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.