I know we didn't have the facility at our base for barrel change, perhaps at the Navy base close by as they had Parkerizing facilities. Once I mentioned changing an FN barrel to the effect of unscrew it and change it...the weapon's Sgt just made fun of the remark. It was like it was the hardest thing to do. Not all of them seemed to be savvy to changing a pipe... The stampings on the knoxform are crude, not a CAL type of job.