← SIG Sauer P320 reference page · This work order as JSON ·
Work order — SIG Sauer P320
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.
| Work order # | |
|---|---|
| Customer | |
| Model on the bench | |
| Serial number | |
| Finish / colour | |
| Received | |
| Technician |
Before you startEducational 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.
- SIG Sauer safety notice — P320 Voluntary Upgrade Program (2017): All SIG SAUER P320 pistols purchased before August 2017, i.e. without the upgraded trigger, sear, striker and mechanical disconnector; P320s made after 2017-08-08 already include the upgraded design. SIG's online serial-number lookup shows whether a given pistol has been upgraded. Voluntary, free upgrade (SIG pays shipping both ways): register online at sigsauer.com/support/p320-voluntary-upgrade/ (serial-number lookup) or call SIG SAUER Customer Service (603) 610-3000 option 1; the pistol is returned with lighter trigger/sear/striker and a mechanical disconnector.
- SIG Sauer limits owner disassembly: Field strip, magazine disassembly, and the section 8 user procedures, including removing the Fire Control Unit from the grip module. The FCU itself is not to be disassembled.
- This work order is written for the SIG Sauer P320. It is reported to cover SIG Sauer M17; SIG Sauer M18; P320 Compact; P320 X-Series; P320 XTEN — if the firearm on the bench is one of those, check the torque notes: values do not always carry over.
Shop difficulty: Tier 1 of 3
The coatable parts come off as units: the fire control unit lifts out of the polymer grip module in the owner procedure and stays assembled (SIG reserves the sear housing for depot), leaving a slide with striker, extractor and sights. Only order matters (slide off before the takedown lever). Pew-Takedown's rating, not the manufacturer's.
Bench time: strip ~15 min, rebuild ~20 min (estimate). Actual: strip ______ rebuild ______
Special tools:
- 90-degree pick — Takedown safety lever spring
- FCU support block (e.g. Gray Guns) — Driving the sear housing pin if the FCU is opened
- dovetail sight pusher (or brass drift and padded vise) — Removing and refitting dovetailed sights for coating
Watch for:
- If the takedown lever is pulled before the slide is off, the fire control unit lifts out with the slide and the two lock together. (disassembly; SIGforum)
- If the FCU itself is opened, every pin pushes except the sear housing spirol pin, which must be driven with the unit supported, and the takedown safety lever spring needs a 90-degree pick. (both; SIGforum)
- SIG restricts disassembly past the manual to its armorers or a professional gunsmith. (both; SIG SAUER)
1. Clear and make safe
- Point the muzzle in a safe direction and keep your finger off the trigger.
- Press the magazine release and remove the magazine.
- Retract the slide fully and lock it open with the slide catch lever.
- Visually and physically verify the chamber is empty.
- Remove all live ammunition from the work area.
2. Disassemble
Manufacturer's video: P320 Field Strip and Cleaning with Chris Cavallaro (SIG SAUER Academy)
https://www.youtube.com/watch?v=pUV6T_GB6To
Field Strip
- Complete the Clear and Make Safe procedure and leave the slide locked to the rear.
- Rotate the takedown lever on the right side of the frame downward about 90 degrees until it stops.
Tip: On some pistols the lever is stiff when new. Thumb pressure, not tools. - Hold the slide, release the slide catch lever, and ease the slide forward off the frame.
- Lift the recoil spring assembly out of the inverted slide.
Warning: It is under spring tension — keep a thumb on it. - Lift the barrel up and out of the slide.
Remove the Fire Control Unit
- Field strip the pistol and set the slide, barrel, and recoil spring assembly aside.
- With the takedown lever still rotated down, grasp the takedown lever and lift the fire control unit up and out of the grip module.
Tip: It lifts out rear-first on most grip modules.
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.
| Component separated | Out | Coated | Back in |
|---|---|---|---|
| Slide assembly | |||
| Recoil spring assembly | |||
| Barrel | |||
| Fire control unit |
| Component | Material | Factory finish | Source |
|---|---|---|---|
| Grip module all P320 models (manual 13.0) | Glass reinforced | — | [3] |
| Grip module P320 models with a metal grip module (models not named) | alloy steel | — | [3] |
| Slide all P320 models (manual 13.0) | stainless steel | — | [3] |
| Frame (serialized fire-control unit) P320 | Stainless Steel | — | [9] |
| Whole firearm P320 Full Size, item 320F-9-B | — | NITRON | [10] |
| Magazine P320 Full Size, item 320F-9-B | STEEL | — | [10] |
4. Reassemble
Manufacturer's video: P320 Field Strip and Cleaning with Chris Cavallaro (SIG SAUER Academy)
https://www.youtube.com/watch?v=pUV6T_GB6To
Remove the Fire Control Unit
- To install into another grip module, seat the front of the fire control unit first, then press the rear down until it sits flush.
- Confirm the fire control unit is fully seated and the takedown lever rotates freely before reassembling the slide.
Warning: A partially seated fire control unit can bind the trigger. Verify with a function check.
Reassembly
- Set the barrel into the inverted slide and seat it fully forward.
- Seat the recoil spring assembly into the cut in the barrel lug and press it down into the slide channel.
- Set the slide onto the frame rails and push it rearward until the slide catch lever will lock it open.
- With the slide locked back, rotate the takedown lever up to horizontal.
- Release the slide and perform the function check.
5. Torque
| Fastener | Specification | Sequence | Source | Applied | Init. |
|---|---|---|---|---|---|
| Sight plate screws (2, rear sight/sight plate, 3/32 in. hex, from bottom of slide) SIG P320 pistols |
20 in-lb 2.3 N·m · 1.7 ft-lb |
Install LCI post and spring into slide; install sight plate and sight onto slide holding LCI post and spring in place; insert sight plate screws from bottom of slide and tighten to 20 in-lbf; then reinstall striker assembly, extractor, extractor pin/spring/plus pin and rear slide cap. Note: 'Sight plate screws are for securing the rear sight and sight plate only.' 8.1 table also lists 20 in-lbf / 2.26 nm. Threadlocker: LOCTITE 243 (per 8.1 table; 'If there is no Nylok® patch present on the fastener, use specified Loctite®') |
[3] p. 81 | ||
| Blanking (optic cover) plate screws (2, T20, top of slide) SIG P320 optic-cut slides |
20 in-lb 2.3 N·m · 1.7 ft-lb |
Place blanking plate into its slot in slide; insert blanking plate screws and tighten. Note: 'Blanking plate screws are for securing the blanking plate only.' CONFLICT: the section 8.1 torque table (p. 77) lists Blanking Plate Screws at 25 in-lbf / 2.82 nm. Threadlocker: LOCTITE 243 (per 8.1 table; 'If there is no Nylok® patch present on the fastener, use specified Loctite®') |
[3] p. 85 | ||
| ROMEO red dot mounting screws (2, 1/8 in. hex) SIG P320 pistols equipped with a SIG ROMEO optic (with or without shroud) |
25 in-lb 2.8 N·m · 2.1 ft-lb |
Insert ROMEO into shroud (if equipped); place ROMEO and shroud assembly on slide aligning holes; install ROMEO screws and torque to 25 in-lbs; refer to ROMEO manual for zeroing. 8.1 table also lists 25 in-lbf / 2.82 nm. Threadlocker: LOCTITE 243 (per 8.1 table; 'If there is no Nylok® patch present on the fastener, use specified Loctite®') |
[3] p. 88 | ||
| Compensator attachment screws (2, T10) SIG P320 models with factory barrel compensator |
20 in-lb 2.3 N·m · 1.7 ft-lb |
Clean and degrease threads of barrel and compensator. Insert barrel into slide. Apply LOCTITE 246 to threads of barrel and compensator. Thread compensator onto the barrel until it stops, then unscrew until vertical slots in barrel align with the screw holes in the compensator. Install compensator attachment screws and apply a final torque of 20 in-lbf. (8.1 table: Barrel Compensator Threads N/A torque, LOCTITE 246.) Threadlocker: LOCTITE 243 on screws; LOCTITE 246 on barrel/compensator threads (8.1 table) |
[3] p. 94 | ||
| Magazine funnel screw, standard funnel (T10, rear of grip module) SIG P320 grip modules with detachable standard magazine funnel |
6 in-lb 0.68 N·m · 0.5 ft-lb |
Threadlocker: LOCTITE 243 (per 8.1 table; 'If there is no Nylok® patch present on the fastener, use specified Loctite®') |
[3] p. 100 | ||
| Magazine funnel screw, AXG magazine well (T10, bottom of grip module) SIG P320 AXG grip modules |
11 in-lb 1.2 N·m · 0.92 ft-lb |
Threadlocker: LOCTITE 243 (per 8.1 table; 'If there is no Nylok® patch present on the fastener, use specified Loctite®') |
[3] p. 100 |
Reported by other sources — not the manufacturer
Not a manufacturer specificationConfirm with the manufacturer or a licensed gunsmith before use. Where these differ from a manufacturer value above, the manufacturer wins.
| Fastener | Reported value | Sequence | Source | Applied | Init. |
|---|---|---|---|---|---|
| Optic mounting screws through plate (T15 6-40 x 9/16) SIG P320 (not M17/M18, not integrated-plate slides) with Forward Controls Design OPF-P320, RMR plate, Trijicon RMR Reported by Forward Controls Design (secondary) — not the manufacturer |
13–15 in-lb 1.5–1.7 N·m · 1.1–1.2 ft-lb |
[4] | |||
| Optic plate to slide screws SIG P320 X-Five Legion, Legion Carry, commercial M17/M18 and Romeo1 Pro/DPP-cut slides with FCD OPF-P320, RMR, RSD plate Reported by Forward Controls Design (secondary) — not the manufacturer |
12 in-lb 1.4 N·m · 1 ft-lb |
[5] | |||
| Optic (sight) to plate screws SIG P320 R1P/DPP-cut slides with FCD OPF-P320, RMR, RSD plate, Trijicon RMR Reported by Forward Controls Design (secondary) — not the manufacturer |
12 in-lb 1.4 N·m · 1 ft-lb |
[5] | |||
| Optic plate to slide screws (M4 x 0.7 x 6 mm) Military-issue M17/M18 (P320 variant) with Forward Controls Design OPF-M17, ACRO plate Reported by Forward Controls Design (secondary) — not the manufacturer |
20 in-lb 2.3 N·m · 1.7 ft-lb |
Threadlocker: VC-3 packet supplied |
[6] | ||
| Aimpoint ACRO P1/P2 mounting screw Military-issue M17/M18 with FCD OPF-M17, ACRO plate, Aimpoint ACRO P1/P2 Reported by Forward Controls Design (secondary) — not the manufacturer |
26 in-lb 2.9 N·m · 2.2 ft-lb |
[6] | |||
| Steiner MPS mounting screw Military-issue M17/M18 with FCD OPF-M17, ACRO plate, Steiner MPS Reported by Forward Controls Design (secondary) — not the manufacturer |
18 in-lb 2 N·m · 1.5 ft-lb |
[6] | |||
| Optic adapter plate mounting screws (Holosun RMR-footprint plate for P320 Romeo1 Pro cut) SIG P320 with Romeo1 Pro optic cut, HOLOSUN adapter plate for RMR footprint (407C/507C/508T/SRO) Reported by HOLOSUN Europe (holosun.eu, operated by Picotronic GmbH, HOLOSUN European distributor) (secondary) — not the manufacturer |
1.4 N·m 12 in-lb · 1 ft-lb |
[7] | |||
| Optic adapter plate mounting screws (Holosun RMR-footprint plate for P320 Romeo1 Pro cut) SIG P320 with Romeo1 Pro optic cut, HOLOSUN adapter plate for RMR footprint (407C/507C/508T/SRO) Reported by HOLOSUN Europe (holosun.eu, operated by Picotronic GmbH, HOLOSUN European distributor) (secondary) — not the manufacturer |
max. 1.7 N·m 15 in-lb · 1.3 ft-lb |
[7] | |||
| Red-dot optic mounting screws (6-32 flat head, supplied) into EGW rear-dovetail sight mount SIG Sauer P320 (non-optics-ready slide with rear dovetail) with the EGW 'Trijicon RMR / SRO, Holosun 407c / 507c Mount for Sig Sauer P220, P226, P229, P320' (replaces the rear sight; for Trijicon RMR/ Reported by Evolution Gun Works (EGW) (secondary) — not the manufacturer |
15 in-lb 1.7 N·m · 1.2 ft-lb |
Remove the rear sight, install the EGW mount in the dovetail, tighten the set screw if applicable, place the optic on the mount, then apply blue Loctite and torque the optic screws. Threadlocker: Blue Loctite on the provided mounting screws (EGW instructions) |
[11] | ||
| Red-dot optic mounting screws (supplied) into EGW rear-dovetail sight mount (Docter/Venom/Viper/FastFire footprint) SIG Sauer P320 (non-optics-ready slide with rear dovetail) with the EGW 'SIG Sauer P220 P226 P229 P320 Red Dot Mount | Fits Vortex Venom, Viper & Burris FastFire | EGW' (replaces the rear sight) Reported by Evolution Gun Works (EGW) (secondary) — not the manufacturer |
15 in-lb 1.7 N·m · 1.2 ft-lb |
Remove the rear sight, install the EGW mount in the dovetail, tighten the set screw if applicable, place the optic on the mount, then apply blue Loctite and torque the optic screws. Threadlocker: Blue Loctite on the provided mounting screws (EGW instructions) |
[12] | ||
| Vortex Venom mounting screws on EGW adapter plate (Romeo1-cut optics-ready slide) SIG Sauer P320 RX / P320 X-Five Optics Ready (Romeo1 cut; not M17 or Romeo1 Pro cut) with the EGW 'Adapter Plate for Sig P320 (Romeo) to Vortex Venom' Reported by Evolution Gun Works (EGW) (secondary) — not the manufacturer |
15 in-lb 1.7 N·m · 1.2 ft-lb |
Threadlocker: Blue Loctite on the provided mounting screws (EGW instructions) |
[13] |
Notes: SIG's P320 manual gives two figures for the blanking (optic cover) plate screws: 25 in-lbf in its torque table and 20 in-lbf in the installation step. The installation step's 20 in-lbf is shown; confirm with SIG if it matters for your slide.
Fit or check on rebuild
- FCU fully seated in the grip module — A partly seated FCU gives a gritty trigger or no reset
- Function check: trigger reset, sear/striker engagement, safeties — Standard post-reassembly check on any pistol whose fire-control parts were removed; a mis-seated spring shows up here, not on the bench
6. Function check
- Verify the pistol is unloaded before each check.
- Rack the slide and press the trigger. The striker should release cleanly.
- Hold the trigger back, rack the slide, release slowly and feel the reset.
- Press the trigger again to confirm the striker releases.
- If the pistol has a manual safety, confirm the trigger is blocked with the safety engaged.
- Confirm the slide locks open on an empty magazine and the magazine drops free.
If any check fails, the firearm is not safe to fire. Stop and see a licensed gunsmith.
Sources
- SIG Sauer P320 Operator's Manual — SIG Sauer, Inc. primary
- SIG Sauer P320 Voluntary Upgrade Program notice (2017) — SIG Sauer, Inc. primary
- SIG P320 Pistols Operator's Manual: Handling & Safety Instructions, 8501909-01 REV11 (Sept 2023), section 8 — SIG SAUER primary
https://www.sigsauer.com/media/sigsauer/resources/OPERATORS_MANUAL_P320_8501909-01_REV11_WEB_FILE_1.pdf - OPF-P320, RMR (product page) — Forward Controls Design secondary
https://www.forwardcontrolsdesign.com/OPF-P320-RMR_p_449.html - OPF-P320, RMR, RSD (product page) — Forward Controls Design secondary
https://www.forwardcontrolsdesign.com/OPF-P320-RMR-RSD_p_344.html - OPF-M17, ACRO (product page) — Forward Controls Design secondary
https://www.forwardcontrolsdesign.com/OPF-M17-ACRO_p_277.html - Adapter plate for Footprint RMR on SIG P320 Romeo 1 Pro (product page) — HOLOSUN Europe (holosun.eu, operated by Picotronic GmbH, HOLOSUN European distributor) secondary
https://www.holosun.eu/en/p/70189674 - SIG SAUER — Voluntary Upgrade Notice (P320 upgrade program customer letter) — SIG SAUER, Inc. primary
https://www.sigsauer.com/pub/media/sigsauer/resources/Voluntary-Upgrade-Notice-1.pdf - SIG SAUER, Inc. — 2019 GDS CATLOG WORKING FINAL LR — SIG SAUER, Inc. primary
https://www.sigsauer.com/pub/media/sigsauer/resources/2019_GDS_CATLOG_WORKING-FINAL-LR.pdf - SIG SAUER, Inc. — 2021 Guide Price List 11 8 — SIG SAUER, Inc. primary
https://www.sigsauer.com/media/sigsauer/resources/2021-Guide-Price-List-11-8.pdf - Trijicon RMR / SRO, Holosun 407c / 507c Mount for Sig Sauer P220, P226, P229, P320 (EGW product page, installation instructions section) — Evolution Gun Works (EGW) secondary
https://egwguns.com/trijicon-rmr-sro-holosun-407c-507c-mount-for-sig-sauer-p220-p226-p229-p320 - SIG Sauer P220 P226 P229 P320 Red Dot Mount | Fits Vortex Venom, Viper & Burris FastFire | EGW (EGW product page, installation instructions section) — Evolution Gun Works (EGW) secondary
https://egwguns.com/vortex-viper-venom-sig-sauer-p220-p226-p229-p320-sight-mount-fits-burris-fastfire-and-docter - Adapter Plate for Sig P320 (Romeo) to Vortex Venom (EGW product page, installation instructions section) — Evolution Gun Works (EGW) secondary
https://egwguns.com/vortex-venom-adapter-plate-for-optics-ready-sigs-cut-for-the-romeo-1-p320-rx-x-five - Seeking stupidity relief: P320 FCU stuck on slide. (Don't remove the takedown lever first!) - Topic — SIGforum anecdotal
https://sigforum.com/eve/forums/a/tpc/f/430601935/m/6910085464 - Building a P320 FCU from parts - Topic — SIGforum anecdotal
https://sigforum.com/eve/forums/a/tpc/f/430601935/m/3440076374?csra=Y&f=430601935&a=tpc&m=3440076374&s=674608412
| Reassembled and function-checked by | Date |
|---|
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.