Glock Factory Recoil Spring Assembly Glock 21 Gen 4

The Glock Gen4 dual captured recoil spring assembly is a factory replacement part for the Glock 21 pistol. The recoil spring assembly is constructed of stainless steel with chrome silicon springs. The Gen 4 recoil spring assemblies are designed to withstand 5,000 rounds before they should be replaced to maintain reliability. This assembly will not work with the Gen2 or Gen3.