Bowkett used the HW system of barrel bolt/locking but didnt use HW componenents. He made an oversize bolt with a flat head instead of a dome and case hardened it. The end of the bolt had a fine thread which screwed into the opposite breech jaws and was locked in position with a flat head screw. The shank of the bolt was slightly shorter than the breech jaw width and the flat head locking screw when screwed into the purpose made case hardened bolt tightened against the jaws.
All included in a 12 ft/lbs conversion including trigger workover and scope stop for
£23.50.Those were the days