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Action Army firing pin lock for the AAP-01 GBB airsoft pistol is an original replacement part no. 45 (AAP01-09-45), also known as the Knocker Lock / Reset Arm. It is part of the hammer mechanism and is responsible for locking and subsequently releasing the Valve Knocker during the firing cycle. Suitable for repairing a worn or damaged mechanism in Action Army AAP-01 and AAP-01C GBB pistols.

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AAP01-BK
One of the most popular gas-powered GBB pistols in airsoft. AAP-01 Assassin GBB by Action Army in matte black finish. A hybrid between the legendary Ruger (design) and Glock (TM / WE G-series magazines). Shoots in semi and full-auto with insane rate of fire. Strong blowback and lightweight polymer frame. Endless upgrade potential – easily converted...
U01-014
Original Polymer Loading Nozzle for AAP-01 / AAP-01C GBB Pistol by Action Army in black. Easy drop-in replacement. Genuine manufacturer part 71 ensures 100% compatibility. Installation requires technical knowledge of GBB pistols.
AAP01C-BK
One of the most popular gas-powered GBB airsoft pistols in an even more compact form. AAP-01C Assassin Compact GBB by Action Army in matte black. Miniaturized hybrid between the iconic Ruger (appearance) and Glock (uses TM / WE G-series magazines). Fires in semi and full-auto with brutal rate of fire. Strong blowback and lightweight polymer frame....
The Action Army AAP-01 Knocker Lock is an original replacement component of the Hammer Housing assembly. In the exploded parts diagram, it is listed as part no. 45 under catalogue designation AAP01-09-45 and is referred as the Knocker Lock, Firing Pin Lock or Reset Arm. Despite its small size, this component plays an important role in controlling gas release and ensuring correct cycling of the GBB mechanism. When the trigger is pulled, the Valve Knocker strikes the magazine release valve and part no. 45 temporarily locks it in the forward position. This keeps the valve open long enough to release the required amount of gas to fire the BB and operate the blowback mechanism. As the slide subsequently moves backwards, the lock is depressed, releasing the Valve Knocker and allowing the magazine valve to close. The entire mechanism is then ready for the next shot. A worn, deformed or broken Knocker Lock can cause blowback problems, irregular cycling or uncontrolled release of gas from the magazine. Replacement is therefore suitable both when repairing a malfunction and when restoring a heavily used AAP-01. The part is primarily designed for the Action Army AAP-01 GBB and, according to available information, is also compatible with the Tokyo Marui R-Series Model 18.
Possible symptoms include irregular or incomplete blowback, cycling problems and uncontrolled gas release. However, the same symptoms can also be caused by other components of the trigger, hammer or gas mechanism, so we recommend correctly diagnosing the fault before replacing the part.
The component is mechanically stressed by the movement of the mechanism during every cycle. With prolonged use, the locking surface may wear, the part may deform or the component itself may become damaged. Mechanical stress may be particularly high during intensive firing and when using FULL-AUTO mode.
Replacement requires disassembling the AAP-01 hammer assembly and correctly positioning the related components and springs. If you do not have experience servicing GBB pistols, we recommend having the installation carried out by an experienced airsoft technician.
| Variants | Part 45 |
| Color | Black |
| Body/receiver material | Metal |