Back in the 70's, I had a Hal Sharon barrel .36 cal. for my rifle. (had a number of barrels for it) This was one of Hal's "deep Buttoned" barrels. I was in his in Kalispel when he was making it.
I don't know what the barrel steel was he used, but some of them split while he was pulling the button through them. Stress much?
Anyway, this barrel was 7/8" across the flats and 34" long. With the breechplug out, you couldn't look at a 60 watt bulb without hurting your eyes. It looked pretty wonky inside with tight & loose
tight/loose, tight/loose bore wavy marks reflecting the light. When loading a patched ball, or cleaning it, I can only describe the feeling as BRRRRRRRRRRRRRRRRRRRRRRRRRRRRT. The entire shop vibrated/shook when he was pulling that button through the barrel.
At rendezvous at Chilliwack BC, maybe 1976, they had a target at 25 yards. High score in 1 minute of shooting. Might have been 2 minutes but I remember 1 minute.
I loaded 30gr. of 3F each time and just rammed a bunch of .375" balls down onto the powder (steel rod), capped and shot at the target. I think I fired 4, times. I had 27 holes in the target
& won first prize, 20 pounds of buffalo meat.
When patched those .375" balls turned in to short bullets, rounded on both ends due to the cupped end on the 5/16" steel rod. Had quite a chamfer on that muzzle. Normal round balls were grossly
inaccurate, but patched .375's shot quite well. It had a .360" bore - well wonky by maybe 2 to 4 thou.