Ted, I'm sure that if the bore condition is good that it can be made to shoot extremely well. I generally don't shoot from a bench rest, preferring prone shooting, but if you check out this ASSRA link you'll see a target shot by my .38-55 CPA rifle. It has an original style chamber ( 6 degree cone from outside of case mouth ). The target was shot with black powder and an 8x scope. The cold bore shot is shown, and of the remaining 11 shots, 9 of them went into a sub-minute of angle group at 200 metres.
This was with breech seated bullets. The same rifle has never given any real accuracy with fixed ammunition.
https://www.assra.com/cgi-bin/yabb/Y...m=1451950847/5
I've got another .38-55 ( C. Sharps 1885 ) with a very poorly cut chamber ( not C. Sharps fault, I had the chamber cut locally ) that only shoots breech seated bullets well. It works quite well with breech seated paper patched bullets over black powder, and breech seated bullets and IMR-4227. This is a 10 shot group at 100m shot with aperture sights. I don't remember what the cause of the low flyer was, but it's certainly capable of minute of angle performance at that distance.
Chris.