YANKEE HILL MACHINE COMPANY NIELSEN PISTON 9MM 1/2X36

Description

The YHM Nielsen Piston is a replacement booster piston built for semiautomatic pistols running a tilting-barrel action. When a pistol suppressor is threaded onto a fixed-barrel host, the added mass at the muzzle prevents the barrel from cycling normally — the Nielsen piston solves this by allowing the suppressor to slide rearward under recoil, generating enough force to unlock and cycle the action. Without it, the host pistol simply will not function reliably with a suppressor attached.

This piston is machined from heat-treated 17-4 stainless steel, which holds up well against the heat and carbon fouling that accumulates in the booster housing over time. The 1/2×36 thread pattern suits 9mm hosts that use that standard pitch. It is designed to mate with YHM’s own YHM-2055 booster housing and is also compatible with a broad range of popular pistol suppressors from other manufacturers. One practical detail worth noting: the piston includes 10 adjustment points for zeroing any point-of-impact shift that a suppressor may introduce — useful if you find your groups moving after threading a can onto the host. At 1.40 oz, the piston itself adds negligible weight to the assembly. One confirmed compatibility note: this piston will not work with the original YHM Sidewinder, but it does function correctly with the Sidewinder M2.

Shipping and availability: This item must ship to a licensed FFL dealer for transfer.