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Work order — Schmidt-Rubin K31

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

Few parts. The barrelled action comes out of the stock after the bands and two screws, and the straight-pull bolt splits into four sub-assemblies by hand. The bolt handle lug carries the striker spring, so bolt reassembly is the only fiddly step, and I found no source reporting it as a trap. Pew-Takedown's rating, not the manufacturer's.

Bench time: strip ~35 min, rebuild ~50 min (estimate). Actual: strip ______ rebuild ______

Special tools:

• hollow-ground screwdrivers — Military screws

Watch for:

• The bolt handle's lug rides in the locking collar's helical slot and compresses the striker spring. Reassembling the bolt means seating that lug against spring load in the right slot. (reassembly; The Firearm Blog)

Tools

• Bore guide — Cleaning from the breech without wearing the throat or the crown. On a surplus rifle the crown is often the difference between accuracy and none.

1. Clear and make safe

1. Point the muzzle in a safe direction and keep your finger off the trigger.
2. Press the magazine catch and remove the magazine.
3. Pull the bolt straight rearward to extract and eject any chambered round.
4. Inspect the chamber and magazine well with a light and physically confirm the chamber is empty.
   Warning: Straight-pull or not, the chamber check is the same.
5. Remove all live ammunition from the work area.

2. Disassemble

Field Strip — Bolt Removal

1. Complete the Clear and Make Safe procedure.
2. Pull the bolt straight rearward to its rearmost position.
3. Press the bolt release catch on the left rear of the receiver and withdraw the bolt straight rearward out of the action.
   Warning: Do not attempt to rotate the bolt handle. This is a straight-pull.
4. Clean the bore from the breech using a bore guide, and clean the bolt face, lugs, and chamber.
   Warning: Always use a bore guide on a surplus rifle. Cleaning rod wear at the crown is a permanent accuracy loss and is very common on milsurp.
5. Stop here for routine maintenance. Bolt disassembly is a separate procedure and is not part of normal cleaning.

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

Reassembly

1. Align the bolt with the receiver raceway.
2. Slide the bolt straight forward into the receiver until it passes the release catch.
3. Cycle the bolt straight back and forward several times to confirm smooth travel and correct locking.
4. Reinstall the magazine and perform the function check.

5. Torque

No manufacturer torque values are recorded for this firearm.

Fit or check on rebuild

• Bolt locks and cocks — The handle lug has to be correctly seated in the collar cam. Standard check, not sourced.
• Re-zero sights or scope — Sights and optics come off for coating, and point of impact must be re-confirmed. This is a standard check, so no source.

6. Function check

• Verify the rifle is unloaded — chamber and magazine — before each check.
• Cycle the bolt and confirm it cocks and closes fully into battery.
• With the action cocked, engage the safety and press the trigger. The striker must not release.
• Disengage the safety without touching the trigger. The striker must not release.
• Press the trigger and confirm the striker releases with a firm snap.
• Load dummy rounds and confirm they feed and eject cleanly.
• If you have any doubt about the rifle’s history, have headspace gauged by a gunsmith before firing live ammunition.
• Confirm the bolt locks positively at the end of its forward stroke — on a straight-pull the locking happens as you push the handle home, and it should feel definite.

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

Sources

1. Karabiner 31 Handbook — Swiss Army primary
2. A look inside the Swiss K31 Bolt — The Firearm Blog secondary
   https://www.thefirearmblog.com/blog/2013/08/28/swiss-k31-bolt/

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.