Criterion M1 Carbine barrels offer superior function and accuracy, as proven by Mark Stout's national record setting performance at the 2017 Camp Perry National Matches. Criterion M1 Carbine barrels are manufactured to mil-spec print #6544006. A new manufacture gas cylinder is installed and crimped to the barrel. Each barrel has a parkerized finish and a .010 short chamber to be installed and headspaced by a qualified gunsmith.