The Monolith is a direct-impingement, gas-operated semi-automatic rifle chambered in 5.56 NATO/.223 Rem ... s extension has also been enlarged from AR-15 to AR-10 proportions.

I brought over a 2-7X variable sight with internal range finder and a mount for the Colt AR-15 commercial rifle ... and less powerful than the 7.62 mm NATO cartridge used in our M14 rifle.