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Work order — Heckler & Koch USP

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 2 of 3

About 52 key numbers (91 pieces in HK's list counting variant rows) with several traps: the lanyard block is under spring tension, the control-lever detent plate is spring-loaded, the trigger-bar detent spring launches if the bar slips, and the disconnector is hard to get back in. Borderline Tier 3 for an LEM or variant-converted gun. 54 parts (USP full size, .40 S&W and 9 mm (incl. LEM sub-list) per this page's transcription; 89 rows, 54 distinct key numbers (highest 52). Compact, USP45 and Tactical/Expert lists omitted.). Pew-Takedown's rating, not the manufacturer's.

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

Special tools:

• HK trigger return spring pliers — Trigger rebound/return spring
• tweezers and a plastic pick — Detent plate, trigger bar detent and flat spring (per the enthusiast guide)
• dovetail sight pusher (or brass drift and padded vise) — Removing and refitting dovetailed sights for coating

Watch for:

• The trigger-bar detent and its spring are held only by the trigger bar; if the bar slips while compressing it, the detent flies. (both; hk-manuals archive (HK enthusiast write-up))
• The lanyard block holds the hammer spring under tension and comes out with it. (both; hk-manuals archive (HK enthusiast write-up))
• The control-lever detent plate is under spring pressure and goes airborne if its pin is pushed out carelessly. (both; hk-manuals archive (HK enthusiast write-up))
• A USP Compact owner lost the disconnector during a trigger conversion and describes it as nearly impossible to install correctly. (reassembly; SIGforum)

1. Clear and make safe

1. Point the muzzle in a safe direction and keep your finger off the trigger.
2. Remove the magazine.
   Warning: A cartridge can be in the chamber whether or not a magazine is fitted, and will fire if the trigger is pulled.
3. Retract and lock the slide fully to the rear.
4. Visually AND physically check with your finger that there is no cartridge in the chamber.
   Warning: HK's instruction: never rely solely on a mechanical device or your memory to decide whether the pistol is loaded.
5. Unload all magazines and remove all live ammunition from the area.

2. Disassemble

Field Strip

1. Complete the clearing and safety check.
2. Depress the slide release and allow the slide to move forward.
3. Hold the pistol so your thumb covers the rear of the frame and your fingers rest on top of the slide.
4. With the firing hand, pull the slide back until the retention tab of the slide release is visible through the recess on the left side of the slide.
   Tip: That recess, not a takedown notch, is the index.
5. With the other hand, press on the axle of the slide release from the RIGHT side of the frame and remove the slide release completely from the LEFT side.
6. Holding the recoil assembly in place, slide the slide with barrel and recoil spring assembly forward off the frame.
   Warning: Keep hold of the recoil assembly. Released under spring tension it can injure someone or be lost.
7. Turn the slide upside down and carefully push the recoil spring forward, up, and out to either the left or right side, separating it from the barrel and slide.
   Warning: The recoil spring assembly is captive. HK does not recommend disassembling it further.
8. Pivot the barrel slightly forward and press upward on the barrel through the ejection port to separate it from the slide.
9. Stop here.
   Warning: HK states that only a certified HK armorer should disassemble the pistol further.

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.

The manufacturer's full parts list (89 parts) is on the reference page.

4. Reassemble

Reassembly

1. Position the barrel in the slide so the muzzle fits the hole in the front of the slide, and the locking block sits within the ejection port with its angled locking surfaces visible along the bottom of the slide.
2. Install the recoil spring assembly so the front of the recoil spring guide rod engages the small hole in the front of the slide.
3. Align the opposing angled locking surfaces on the rear end of the recoil spring guide rod with those on the bottom of the barrel locking block.
   Tip: This alignment is the whole trick to USP reassembly.
4. Push the rear of the recoil spring assembly forward far enough that the recoil spring retainer engages the shelf on the front of the barrel locking block.
5. Hold the slide in the non-firing hand with your thumb keeping the rear of the recoil spring assembly in place.
6. Check the position of the sear axle on the frame and make sure it does not protrude from either side.
   Warning: A proud sear axle will stop the slide going on, and is easy to miss.
7. Hold the frame in the firing hand and position the rear of the slide above the front edge of the frame.
8. Slowly draw the slide back onto the frame, pressing down on the disconnector with the rear of the slide so the metal inserts in the frame enter the grooves inside the slide.
9. Retract the slide until the recess on its left side sits over the slide release axle hole, and hold it there.
10. Insert the slide release from left to right into the frame until it is flush with the side of the frame.
11. Clear the pistol and check it for correct assembly and operation.
    Warning: HK requires a function check every time the pistol has been disassembled. Match it to your control variant.

5. Torque

No manufacturer torque values are recorded for this firearm.

Reported by other sources — not the manufacturer

Notes: The manufacturer's documents give no torque value. They say: "DO NOT OVER TIGHTEN THREAD PROTECTORS." (Heckler & Koch USP Operator’s Manual, PDF p. 9 ("Instructions for use of HK thread protectors")) "Secure the bases by tightening the two 3 mm Allen screws on the right side of the frame, DO NOT OVERTIGHTEN (see figure 35 & 36)." (USP Operator's Manual (3_1_21), p. USP Match counterweight section)

Fit or check on rebuild

• Control-lever variant parts match — USP variants (1-10) and the 2005 catch/hammer revision use different detent plates and catches; mixed parts will not function
• 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 with no magazine inserted before each check.
• With the hammer down, press the trigger for a double-action hammer fall (on DA/SA variants).
• Cock the hammer, engage the safety or decocker as fitted, and confirm the expected behaviour: a safety must block the trigger; a decocker must lower the hammer without the firing pin being struck.
• Rack the slide and press the trigger for a single-action break.
• Hold the trigger back, rack the slide, release slowly and confirm the reset.
• Confirm the slide locks open on an empty magazine.

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

If it won't go back together

Sources

1. Heckler & Koch USP Operator’s Manual — Heckler & Koch primary
   https://hk-usa.com/wp-content/uploads/2026/08/USP-Operators-Manual-8.25.2026-FINAL.pdf
2. USP Operator's Manual (3_1_21) — Heckler & Koch USA (Heckler & Koch, Inc.) primary
   https://hk-usa.com/wp-content/uploads/2023/09/USP-Operators-Manual-3_1_21-1.pdf
3. Trijicon RMR / SRO, Holosun 407c / 507c Mount for HK USP (EGW product page, installation instructions section) — Evolution Gun Works (EGW) secondary
   https://egwguns.com/trijicon-rmr-sro-holosun-407c-507c-mount-for-h-k-usp
4. HK USP Red Dot Mount | Fits Vortex Venom & Burris FastFire (EGW product page, installation instructions section) — Evolution Gun Works (EGW) secondary
   https://egwguns.com/vortex-viper-venom-hk-usp-sight-mount-fits-burris-fastfire-and-docter
5. Detailed Disassembly of The Heckler & Koch USP (Dr. Killjoy, ed. Jeray) — hk-manuals archive (HK enthusiast write-up) anecdotal
   https://hk-manuals.s3.amazonaws.com/files/Armorer/USP/Detailed_Disassembly_of_the_HK_USP.pdf
6. Sigs vs HK's - Topic — SIGforum anecdotal
   https://sigforum.com/eve/forums/a/tpc/f/430601935/m/6900042305

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.