Part Number: 1005-00-726-6342 (Buffer, recoil mechanism)Part Number: 1005-00-832-9616 (Buffer, recoil mechanism)Part Number: 1005-00-908-4141 (Buffer, recoil mechanism)Part Number: 1005-01-015-0421 (Buffer, recoil mechanism)Part Number: 1005-01-081-5624 (Buffer, recoil mechanism)