Gemtech Piston, GM-45 LID for USP

The Gemtech GM-45 Piston for USP (brand part no. 12191) is a booster piston built for Gemtech’s GM-45 suppressor line on HK USP-pattern host pistols, letting the barrel reciprocate independently of the suppressor’s added mass. That independent movement keeps a recoil-operated .45-caliber pistol cycling reliably once a can is mounted, rather than short-stroking. As a wear item, the piston can be replaced on its own as springs and seals age, without buying a new suppressor. It ships as a standalone service part, separate from the suppressor tube.

Key Specifications

• Built as a piston for the GM-45 suppressor line, letting the barrel cycle independently of the suppressor’s mass.
• Fitted specifically for the USP-pattern host pistol, matching its barrel and mounting geometry.
• An overall length of 5.8 inches covers the full piston assembly.

Frequently Asked Questions

What pistol is this piston built for? It’s fitted for HK USP-pattern host pistols running Gemtech’s GM-45 suppressor.

How is this different from the MK23 version? This piston is fitted for USP-pattern hosts, while the other GM-45 piston is fitted for MK23-pattern hosts.

Is this a wear item? Yes, pistons are a service part that can wear over time and be replaced independently of the suppressor.

Buy the Gemtech Piston, GM-45 LID for USP

Order the Gemtech GM-45 Piston for USP from our Lubbock, Texas gun shop for fast, direct shipping. See more pistol suppressor parts in our Class 3 parts & accessories category.