The SilencerCo Osprey/Octane piston (brand part no. AC25) is a 9mm replacement piston built for shooters running SilencerCo threaded-barrel setups. Machined from 17-4 stainless steel and heat-treated for durability, it forms the moving half of the Nielson device that lets a pistol barrel unlock and cycle normally while the suppressor stays put. Swapping in a fresh piston is the easiest way to move a host suppressor to a new caliber or barrel, or to replace a worn factory piston without sending the whole can back. Pair it with a fixed barrel spacer if the host uses a fixed-barrel setup instead of a tilting barrel. It is a simple, low-cost part that keeps a suppressor cycling reliably across multiple host firearms.

Key Specifications

• Chambered for 9mm hosts, matching the piston’s female threading to the barrel’s caliber.
• Cut with a 1/2-28 tpi thread pattern to mate directly with SilencerCo threaded barrels.
• Machined from 17-4 stainless steel for corrosion resistance and long service life.
• Heat-treated for added durability, standing up to repeated cycling under recoil.
• Measures 2.1 inches in length, sized to fit inside the Nielson device housing.
• Built as a Piston-type component, the moving half of SilencerCo’s Nielson device.
• Compatible with Osprey and Octane series suppressors as a direct-fit replacement part.
• Also fits the Omega K Series, Hybrid 46, and Omega 36M lines, extending replacement options across hosts.
• Weighs about 0.1 pounds shipping weight, adding negligible bulk to a host suppressor.

Frequently Asked Questions

Will this piston work with a fixed-barrel host? Not on its own; use a fixed barrel spacer alongside it so the piston is held stationary instead of cycling with the barrel.

What is a Nielson device? It’s the internal mechanism that lets a pistol-caliber suppressor move slightly on the barrel, allowing the host firearm’s action to cycle normally.

Does this piston fit other SilencerCo hosts besides Osprey and Octane? It’s built around the same threading and Nielson device platform used across several SilencerCo pistol-caliber suppressors, so check your specific host’s spec sheet before ordering.

Buy the SilencerCo Osprey/Octane 9mm Piston (1/2-28)

Keep a SilencerCo SilencerCo host suppressor running smoothly with a properly threaded replacement piston. Browse our full Class 3 parts and accessories selection and order this piston as soon as it’s ready to ship from our Lubbock, Texas gun shop.