Timerzanov Airsoft scrutinizes the BOLT Airsoft B4 Devgru BRSS, which is based on the HK416 Devgru... "The BOLT brand, established in Taiwan since 2011, creates and produces high-end, full-metal replicas aimed at MilSim, Survivalists and players looking for a qualitative replica with something more. BOLT has deposited the BRSS system (Bolt Recoil Shock System) which allows, in addition to the back and forth of the breech on each shot, to simulate a recoil effect, as on a real weapon, by a countermass system. The B4 DEVGRU (inspired by the diminutive Naval Special Warfare Development Group, an American counterterrorism and special operation unit) uses a full metal M4 body, the firing modes are in red for better visibility, a modernized telescopic stock, a RIS handguard, and a quick detach silencer."