EOTech HWS XPS-2 A single 8g CO2 cylinder

A single 8g CO2 cylinder should provide 25 shots worth of ammo

Unlike other slings on the market

just like the standard live M4A1

semi & full Receiver Extension 6 Position Mil-Spec 7075-T6 Aluminum Buttstock Magpul CTR  Stock Pistol Grip Magpul K2 XL Pistol Grip Training Suppressor Blue Can

has been classified as a non-firearm by the ATF and cannot chamber a live round

EOTech HWS XPS-2 A single 8g CO2 cylinderThe HWS XPS 2 is the non night vision version of EOTech's shortest and lightest HWS sight so far. The CR123 lithium battery configuration of the XPS 2 provides additional rail space, leaving more room for rear iron sights or magnifiers. Also offering water resistant capability up to 10 feet, the XPS 2 is a great compact and lightweight option for the UNIT4 Training Rifle.