I ran over the cylinder with my old dial calipers and got .450 all the way around. I'll scrub it real good and check it again afterward. I expect opening the throats to a uniform .4525 would only make it shoot better.
Doing it that way wouldn't work for me...at least that I would rely on it...for a comparison, yes, but not for a real diameter.
I just take out the cylinder, grab a .452 bullet and see if it will slip through all the throats. I haven't seen a Ruger BH (mostly older frame) that didn't have 2-3 that were too tight. Some way down there at 449. I ream them all to .4525 then check the barrel.
Depending on the result of slugging the barrel, a couple more thou on the cylinder might be even better.
