The M16/M4 conversion will work in any brand, type or length of AR platform to include piston guns (i.e. H&K 416, LWRC). Designed so the weapon’s dust cover will not close always providing the blue indicator of a safe converted weapon. This is a CCMCK Kit that includes a UTM Face Mask. M16/M4 Series MMR/BBR/SBR Conversion is uniquely designed to prevent the discharge of traditional 5.56mm/.223 “live” ammunition (5.56 NATO, 5.56 x 45mm, and .223 Remington). Fail-Safe is achieved by utilizing an offset firing pin design, which will only work with the rim fire primer used in the UTM Cartridge, but not with a “live” center fire cartridge. In the event a 5.56mm “live” cartridge is chambered and the trigger is pulled, the Conversions offset firing pin will strike outside the primer pocket of the 5.56mm “live” round. This makes it impossible to detonate the “live” cartridge in the UTM converted weapon.