SilencerCo AC59 Osprey/Octane Piston 1/2x28 XL 9mm Stainless

The SilencerCo AC59 is a replacement piston purpose-built for the Osprey and Octane series of 9mm pistol suppressors. This extended-length (XL) piston is threaded 1/2"-28, making it the correct fit for 9mm pistol barrels with longer threaded protrusions than a standard profile can clear.

The AC59 piston is machined from 17-4 stainless steel and then heat treated for maximum durability under the repeated recoil and pressure of suppressed fire. Pistons are the wear component on a fixed-barrel suppressor system: they thread onto the host pistol's barrel and the suppressor body indexes off the piston face, so choosing the right thread pitch and length is essential for proper alignment, concentric lockup, and reliable function of the Osprey or Octane.

A stainless finish provides strong corrosion resistance for shooters who run their suppressor in wet, humid, or sweat-heavy range environments. The XL variant adds extra length over the standard 9mm piston to clear the longer shoulder found on common 9mm pistol threaded barrels. Suppressor pistons should be inspected periodically for splits, cracking, or excessive wear and replaced as needed.

Whether you're configuring a new 9mm host pistol for your Osprey or Octane or replacing a worn piston on an existing setup, the SilencerCo AC59 offers a direct-fit, factory-spec solution engineered by the original manufacturer.