PWS .578X28 PISTON BLK

Description

The Primary Weapons Systems .578×28 piston is a replacement and conversion component for suppressor-ready pistol barrels threaded to that specification, most commonly found on .45 ACP and 10mm platforms. It serves shooters who run a Nielsen device-style suppressor mount and need a piston matched to their host firearm’s thread pitch, or who are swapping the same suppressor between multiple hosts with different threading.

A piston in this context is the part of the Nielsen device that translates rearward pressure from the suppressor into the cycling motion a tilting-barrel semi-automatic pistol needs to function reliably. Without the correct piston, a suppressor mounted on a tilting-barrel pistol will bind the slide and prevent cycling — the piston decouples that motion. Getting the thread pitch right is the critical fit point, and the .578×28 designation here refers to the barrel-side threading this piston is designed to engage.

Primary Weapons Systems manufactures this piston from 17-4 stainless steel, a grade chosen for its combination of corrosion resistance and mechanical strength after heat treatment — both relevant properties given the environment a piston operates in at the interface between a hot barrel and a suppressor body. The construction is intended to hold up through sustained use without dimensional changes that would affect timing or fit. For shooters running a compatible suppressor across different pistol hosts, having a correctly threaded piston for each host is what makes that modularity practical.