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Work order — Mossberg 930

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 2 of 3

Only 43 listed items (45 pieces), but the gas system is a six-part stack on the magazine tube with an orientation-sensitive seal ring and split gas rings that are peeled off with a screwdriver, the trigger housing is a complex assembly Mossberg reserves for a gunsmith, and the magazine spring is heavily loaded. Low Tier 2. 43 parts (Mossberg 930/935 parts list, complete gun; 43 rows, trigger housing listed as one assembly). Pew-Takedown's rating, not the manufacturer's.

Bench time: strip ~45 min, rebuild ~65 min (estimate). Actual: strip ______ rebuild ______

Special tools:

• Thin flat screwdriver — Peeling the split gas rings off the piston
• Punch no larger than 1/8 in. — Trigger housing pins and link pin

Watch for:

• The gas system comes off the magazine tube as a stack (seal ring, piston assembly, spacer tube, pusher, return spring, forearm retainer) that must go back in order, with the seal ring's angled face outward. (reassembly; O.F. Mossberg & Sons, Inc.)
• The split outer and inner gas rings are pried and peeled off the piston with a screwdriver held while the piston is rotated, and must be refitted the same way. (both; O.F. Mossberg & Sons, Inc.)
• The trigger housing is a complex assembly Mossberg says must not be taken apart outside a service centre or by a gunsmith, and the hammer must not be dropped with it out. (both; O.F. Mossberg & Sons, Inc.)
• The magazine spring is under considerable pressure and extends to full length when the end cap comes off. (both; O.F. Mossberg & Sons, Inc.)

1. Clear and make safe

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. Pull the bolt handle rearward to eject any chambered shell and lock the bolt open.
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, inspect the chamber and look up the magazine tube with a light.
   Warning: The chamber AND the tube. A shell hung up in the tube is easy to miss.
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. Unscrew the magazine cap from the end of the magazine tube and remove the forend.
3. Pull the barrel forward off the magazine tube and out of the receiver.
4. Slide the gas piston, seals, and spacer off the magazine tube, noting the order and orientation of each.
   Warning: Note the order and which way each part faces. Reassembled wrong, the gun will not cycle.
5. Pull the bolt handle out of the bolt.
6. Slide the bolt assembly forward and out of the receiver.
7. Push out the trigger group pin and lift the trigger group out of the receiver.

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 (43 parts) is on the reference page.

4. Reassemble

Reassembly

1. Install the trigger group into the receiver and insert its pin fully.
2. Slide the bolt assembly into the receiver, engaging the link with the recoil spring plunger.
3. Install the bolt handle into the bolt.
4. Slide the gas piston, seals, and spacer back onto the magazine tube in the correct order and orientation.
   Warning: Check against a parts diagram if you are unsure.
5. Set the barrel into the receiver with its extension seated fully and its ring over the magazine tube.
6. Install the forend and thread the magazine cap on, hand-tightening firmly.
   Warning: A loose magazine cap causes malfunctions and lets the barrel move. Check it before every use.
7. 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: "Install the stock nut spacer and the stock nut. Do not over-tighten the stock nut." (930 / 935 Owner's Manual (doc 16888), PDF p. 26) "Replace the recoil pad. Do not over-tighten the screws." (930 / 935 Owner's Manual (doc 16888), PDF p. 26)

Fit or check on rebuild

• Seal ring orientation — The angled face must face outward or the gas system leaks and the gun short-cycles.
• 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 by hand and confirm the bolt locks fully into battery.
• 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.
• Confirm the bolt locks open when retracted and releases with the carrier release.
• Load two dummy shells into the magazine and confirm they feed and eject one at a time.
• Confirm the magazine cap is tight.

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

Sources

1. Mossberg 930 Autoloading Shotgun Owner’s Manual — O.F. Mossberg & Sons, Inc. primary
2. 930 / 935 Owner's Manual (doc 16888) — O.F. Mossberg & Sons, Inc. primary
   https://resources.mossberg.com/hubfs/manuals/16888-930-935-Owners-Manual.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.