Griffin Armament GP5 (General Purpose), Suppressor, 6.25, 556NATO, 17-4PH Stainless Steel, Black Finish, 12.9oz, Direct Thread GAGP5-W The GP (General Purpose) suppressors were designed to provide the customer with a lightweight, durable, and affordable suppressor for general use. Constructed entirely of 17-4 stainless steel and utilizing our patented baffle technology, GP suppressors are both durable and high performance. Front and rear 3/4" ( or 19mm) wrench flats provide options for traditional use or forend rail integrated applications. GP suppressors come pre-drilled with a .125" hole for pinning to create one stamp guns. The GP5 can be pinned on a barrel as short as 10.5" The GP5 is a .22 caliber aperture silencer rated for use up to and including 220 swift. The GP series provides quality, engineering, construction, versatility, and affordability in one.