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Work order — Heckler & Koch MP5

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

This is the G3 family in 9 mm, and the HK SP5 list has 49 numbered parts with the trigger housing as one assembly. The strip has the same traps: loose rear-sight springs, plungers and balls, the cocking-support clamping sleeve, the trigger housing spring legs, and a locking piece matched to its carrier. Bolt gap has to be measured afterwards. 45 parts (complete semi-automatic SP5 (the civilian MP5-pattern pistol/carbine with the same roller-delayed action) per the HK 'SP5 Parts List & Exploded View': keys 1-39 plus the 3 not-pictured items (locking ). Pew-Takedown's rating, not the manufacturer's.

Bench time: strip ~55 min, rebuild ~80 min (estimate). Actual: strip ______ rebuild ______

Special tools:

• HK rear sight adjustment tool — Rear sight drum
• Roll-pin punches — Clamping sleeves
• Feeler gauges — Bolt gap
• Extractor spring tool / small pick — Extractor spring loop

Watch for:

• The rear sight drum sits on loose springs and plungers, and the sight base on a ball and spring; they are not captive and fly when the drum comes off. (both; Heckler & Koch, Inc. International Training Division)
• The cocking handle support is held by a clamping sleeve (roll pin) that only lines up with both holes in one handle position. (both; Heckler & Koch, Inc. International Training Division)
• In the trigger housing, spring legs have to be positioned correctly as the sleeve and spring go back. (reassembly; Heckler & Koch, Inc. International Training Division)
• The locking piece and bolt carrier work as a matched pair; mixing them changes function. (reassembly; Heckler & Koch, Inc. International Training Division)

Tools

• Punch or the tip of a cartridge — Pushing out the stock and trigger group push pins if they are tight.

1. Clear and make safe

1. Point the muzzle in a safe direction and keep your finger off the trigger.
2. Place the selector on SAFE.
3. Press the magazine release and remove the magazine.
4. Pull the cocking handle fully to the rear and lock it into its forward notch to hold the bolt open.
5. Inspect the chamber and magazine well with a light and physically confirm the chamber is empty.
6. Release the cocking handle from its notch and let the bolt go forward under spring pressure.
   Warning: Do not ride it forward. Let it slam.
7. Remove all live ammunition from the work area.

2. Disassemble

Field Strip

1. Complete the Clear and Make Safe procedure with the selector on SAFE, the magazine out and the bolt released forward.
2. Push in the locking pin or pins for the back plate and pull them out.
   Tip: The full-size gun has one back plate pin; the K variant has two. The pins can be pushed in from either side of the receiver.
3. Remove the back plate or buttstock to the rear.
4. Remove the pistol grip and trigger group downwards.
5. Pull the bolt group and recoil spring rearwards out of the receiver.
6. Push in the locking pin for the handguard and pull it out.
7. Pull the handguard towards the muzzle, then downwards, to remove it.
   Tip: Forward first, then down. It does not come straight off.

Bolt Group Disassembly

1. Strip the firearm into assembly groups first.
2. Turn the bolt head and locking piece clockwise.
3. Remove the bolt head and locking piece from the bolt carrier by bringing them forward.
4. Remove the firing pin and its pressure spring forward out of the bolt carrier.
5. Clean the bolt head, its roller recesses, the locking piece and the carrier interior.
   Warning: HK's published strip stops here. Driving the rollers out of the bolt head is armorer work and is not part of routine 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

Bolt Group Disassembly

1. To reassemble: push the pressure spring onto the firing pin and place both into the locking piece.
2. Press the locking piece completely into the bolt carrier and hold it there.
   Warning: The smooth side of the locking piece faces the bottom of the bolt. Check this before going further.
3. Turn the locking piece counter-clockwise a quarter turn until it reaches its assembly position.
4. Place the bolt head onto the locking piece with the extractor upwards.
5. Turn the bolt head counter-clockwise a quarter turn until the connecting piece audibly and tangibly snaps into place.
   Warning: You should hear and feel it. If it does not snap, it is not assembled.

Reassembly

1. Assemble the bolt group.
2. Place the handguard onto the receiver from below and press it rearwards.
3. Push the handguard locking pin into the receiver.
   Tip: Locking pins can be pushed in from either side.
4. Insert the bolt group and recoil spring into the receiver from the rear.
5. Cock the hammer, then insert the trigger group into the receiver and rotate it upwards.
   Warning: Cock the hammer first. This is the step people miss when the trigger group will not go in.
6. Insert the back plate or buttstock into the receiver.
7. Push the back plate locking pin or pins into the receiver.
8. Pull the cocking handle fully back and release it sharply, then 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: "Tighten the set screw by turning clockwise with Phillips-head screwdriver." (Heckler & Koch SP5 Series Operator's Manual — same roller-delayed action, semi-automatic, PDF p. 21 (rear sight windage adjustment)) "Only remove the Picatinny rail scope mount if it is damaged." (Operator's Manual SP5 Series (5.12.2026 FINAL), PDF p. 25)

Fit or check on rebuild

• Bolt gap — Measured with feeler gauges after reassembly; out of range means roller/locking piece work
• Rear sight zero — The drum and base come off and the rifle must be re-zeroed
• Trigger function — Pressure fork and hammer spring seating checked with a function check

6. Function check

• Verify the weapon is unloaded with no magazine inserted before each step.
• Pull the cocking handle fully rearward and release it sharply. The bolt should go fully into battery.
• With the selector on SAFE, press the trigger. The hammer must not fall.
• Move the selector to semi-automatic, cock the action, and press the trigger. The hammer should fall.
• Hold the trigger back, cock the action, and release the trigger to feel the disconnector reset.
• Confirm the cocking handle locks into and releases from its notch cleanly.
• Confirm both push pins are fully seated and the stock and trigger group are secure.
• If the bolt does not go fully into battery, do not fire. Have the bolt gap checked.

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 MP5 Submachine Gun Operator's and Armorer's Manual — Heckler & Koch GmbH primary
2. Heckler & Koch SP5 Series Operator's Manual — same roller-delayed action, semi-automatic — Heckler & Koch primary
   https://hk-usa.com/wp-content/uploads/2026/09/SP5-Series-Operators-Manual-9.11.26-FINAL.pdf
3. Operator's Manual SP5 Series (5.12.2026 FINAL) — Heckler & Koch USA (Heckler & Koch, Inc.) primary
   https://hk-usa.com/wp-content/uploads/2026/05/SP5-Series-Operators-Manual-5.12.2026-FINAL.pdf
4. MP-5 Armorers Instruction — Heckler & Koch, Inc. International Training Division primary
   https://archive.org/download/MManuals/HkMp5ArmorersManual.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.