M1icon carbine Criterion barrels sold by Tradeex Canadaicon are very good quality, and appear to be MIL-SPEC, except they are longer by 0.75". However, they are not parkerized, have no gas piston or nut, and, as mentioned, have to be reamed to correct headspace. Your carbine would need to be de-registered also to get it out of the RCMP Restricted classification. These longer barrels should be professionally installed, if more info required, please send a PM to me here or on GCN.