As has been stated, CVA St. Louis Hawken barrel in .50 is 28” long and 15/16” across the flats. I also had a CVA .54 barrel that was 28” long and 15/16” across the flats, but I believe .54’s could also be 1” across the flats. Also, as has been stated, Bobby Hoyt can remove, and has removed, a CVA breech plug, and bored out the barrel. The question is, will he?