SilencerCo AC22 Osprey/Octane Fixed Barrel Spacer 17-4 Stainless Steel

The SilencerCo AC22 Fixed Barrel Spacer is a drop-in replacement part designed for the Osprey and Octane series suppressors. It is intended for use on firearms with fixed barrels such as rifles and submachine guns, where the barrel does not reciprocate with each shot and a standard spring-loaded piston assembly cannot function.

When installed, the AC22 spacer takes the place of the booster spring inside the Nielsen device, locking out the spring travel so the Osprey or Octane can be safely and reliably used on a fixed-barrel host. This makes it an essential accessory for shooters running these silencers on platforms that do not provide the rearward energy needed to cycle a conventional piston.

The spacer is precision-machined from 17-4 stainless steel and then heat-treated for maximum strength, wear resistance, and long-term durability under repeated firing schedules. The stainless finish resists corrosion and stands up to the heat and fouling generated by suppressor use.

Compact and lightweight, the AC22 installs in seconds using the same piston housing as the standard booster assembly, with no permanent modification required. Simply remove the booster spring, drop in the spacer, and reassemble. It fits the SilencerCo Osprey and Octane suppressor families.