Walks ,
I think it just depends on how much slop they start out with . I suspect that Rugers are a little bit like the old Chrysler engine line when it comes to barrels and cylinders . Until the 383 couldn't smog anymore it wasn't uncommon to see one on a virgin tear down with 10,15,20,even,30 over pistons in it or an base 2V with a truck cam and and flat top pistons . They built them to a basic tolerance if they had a blem in a cylinder wall or an over/cam bearing they simply ran it through the bore line until it was gone or stuffed whatever the blem rework cam of the day was in it . Sometimes the parts resulted is a real milage maker and sometimes they were really hard on tires . Ruger I suspect has a gauge station for cylinders over/on/under and a barrel gauge station so when the cylinder guy gets it he just hangs the long bearing short cylinder (eg) in the frame with the undersized base pin . As a result sometimes you get a hermetic bank vault and sometimes you get one that is ready for the long bearing standard cylinder and and fat base pin after 2,000 rounds or you get one like yours that was 0/0/0 under and assembled wet .
I had an untouched 1917 , 8/18 assy , that had almost no bolt drag , no bolt ding , and less cylinder gap than headspace . It had 6 perfect .4530 throats and when slugged from the muzzle dropped a .4513 slug out zero bump or drag . The breach poured .4518 and looking at the closed locked hammer down cylinder and barrel all 6 holes had visually no mouth . It was about as close to perfect as one gets and it came out of a plant that was making some 5,000/day hand fit pistols . Sure S&W was known for that kind of quality but I'd lay money that in 1918 they didn't fit that tight out 8 spec buckets more than 1/10,000 .
The Bicentennial BlackHawk I had was quite unremarkable dead in the middle of cyl gap , end play you could feel but not measure and headspace on the short side . Throats were in pairs from .452-4545 and the first time out it shot 3 right together , out but close enough , and 1 that made me question my abilities . With them lapped up to .4535+ for the .4515 barrel I can live with it . The same hole is still wild but it's inside 7/8" per 10 yd instead of 2" per 10 . I bought 2 ACP cylinders for it the first needed an .002 shim and had about .0055 cyl gap but nice even throats that would chamber .454 . The second shared the .453s with the S&W 1917 no flyers and needed to have the bluing and a machine blem/scratch removed off the nose for zero slop free turn and .0025 cyl gap and zero hang ups after 500 rounds over 3 days . I didn't get it until it was 30 yo but it had significant holster wear . It also wasn't a convertible so it never had a second cylinder fitted . The short cylinder was to eventually be a Schofield to let the rims take up the end play but that never happened for me .