My Single Ten had chambers of various sizes, all of them tight when compared to an older Single Six. Cartridges dropped right in some of them, but had to be shoved into others. A friend has a new Bearcat Shopkeeper that had the same problem. The Shopkeeper's ejector rod will not push empties all the way out, and they were sticking in the tight chambers. My buddy broke a couple of fingernails trying to pull out empties when he took it to the range for the first time.
We fixed the problems by reaming all of the chambers to standard dimensions with a 22 cylinder reamer from Brownell's, part number 513-051-220WB. Cartridges now drop right in with no problem, and empties eject from the Bearcat with having to break a fingernail pulling them out. The Bearcat shot a quarter-sized 6-shot group at 10 yards after the cylinder was reamed. As I recall, the Single Ten shot a nice tight group from a rest at 20 yards, but we didn't get around to measuring it. We are both pleased with the results.
Other folks have had good luck with the sandpaper-on-a-dowel treatment, but the reamer worked great for us and sized all of the chambers to the exact same dimensions.