SilencerCo Piston AC1346 | .578×28 XL | 17-4 SS

This SilencerCo piston (AC1346) is a service and replacement component intended for use with compatible SilencerCo threaded barrels and host firearms. It is manufactured from heat-treated 17-4 stainless steel to provide durability under repeated cycling. The piston is part of the Nielson device and is designed to move to allow semi-automatic unlocking of pistol barrels; a Fixed Barrel Spacer can be used for fixed-barrel installations.

Product Specifications

• The model is listed as Piston.
• The manufacturer part number is AC1346.
• The material is specified as 17-4 stainless steel and is heat-treated for durability.
• The thread pattern is .578 x 28 XL.
• The NFA thread pattern is .578×28.
• The size designation is XL.
• The piston functions as part of the Nielson device to enable semi-automatic cycling and barrel unlocking.
• The piston uses female threading to attach to SilencerCo threaded barrels.
• A Fixed Barrel Spacer is available for fixed-barrel applications where applicable.
• The product type is categorized as Accessory-Silencer Accessories.
• Compatible models include Omega K Series, Hybrid 46, Hybrid 46M (with Charlie Piston Mount), Osprey Series, Octane Series, and Omega 36M (with Charlie Piston Mount).
• The UPC is 817272015287.

This piston provides a direct replacement or spare part option for shooters and armorers maintaining or reconfiguring SilencerCo-threaded hosts. It is a purpose-built component for range service, maintenance, and caliber/host conversions where modular piston swaps are required. Its 17-4 stainless construction and heat treatment focus on sustained durability under repeated cycling.