COWCOW Hammer Spring 140% / 200% Set, AAP-01

The COWCOW Hammer Spring Set for the AAP-01 contains two reinforced hammer springs – one 140% and one 200% – for the Action Army AAP-01. The hammer spring is a torsion spring that drives the hammer forward against the magazine's release valve, and with two strengths in the pack you can choose how much extra force your setup needs.

On an AAP-01 with the stock spring, the hammer strike can be too weak, especially when the gas is cold or when the pistol has been upgraded with stronger recoil and nozzle springs. The result is incomplete cycles and inconsistent gas release. A stronger hammer spring opens the magazine valve more decisively, giving a stronger blowback kick – and 140% and 200% cover a moderate upgrade and a more aggressive build respectively.

Features of the hammer spring set

Advantages over the stock spring:

• Two strengths in one pack: 140% for moderate reinforcement and 200% for upgraded builds – you can test both without buying two products.
• Stronger blowback: The harder hammer strike sends more gas to the slide and gives a more pronounced recoil kick.
• High-strength spring steel: Keeps its tension better over time than a tired original spring.
• Better in the cold: A stronger strike helps open the magazine valve properly when the gas loses pressure at low temperatures.
• For AAP-01: The manufacturer states compatibility with the Action Army AAP-01 – the platform where the hammer spring is most often the first step in an upgrade.

Maintenance and safety

• If BBs do not feed correctly because the gas is too weak, COWCOW recommends removing a spacer – or having a technician adjust it.
• A stronger hammer spring can increase velocity – chrono the pistol after fitting and stay within the site's limits.
• De-gas and remove the magazine before disassembly; the hammer spring is under tension in the hammer housing.
• Fitting requires experience – our workshop in Aulum, Denmark can fit the spring and match it to the rest of your AAP-01.