Howdy
First, you have to define just how sloppy the cylinder is.
There are three different elements to define.
1. Endshake: The amount of loose travel forward and back the cylinder exhibits when locked in battery.
2. Rotational Play: The amount the cylinder is free to rotate when locked in battery.
3. Wobble: The amount of angular play the cylinder exhibits when locked in battery.
Without putting a number on each of these values, it is impossible to determine if your Ruger cylinder is 'sloppy' or not.
Endshake is easy to determine. With the cylinder in battery, push the cylinder as far forward as possible and insert the largest shim that will fit between the rear end of the barrel and the face of the cylinder. Then repeat with the cylinder pushed as far back as possible. The difference will be the amount of Endshake. Although zero Endshake is desirable, a few thousandths of Endshake is common, and not the end of the world.
Rotational Play is more difficult to determine. Ideally it should be measured in degrees, but that is pretty difficult to do. So an alternative is to measure in thousandths of an inch how far the cylinder is free to rotate at its circumference from one extreme to the other. I'm playing with my old Blackhawk 45Colt/45ACP convertible that I bought back in 1975 right now. I would guess the cylinder is able to rotate a total of about .010 in total, from one extreme to the other, just using my calibrated eyeball. I have been shooting this revolver for over 40 years, and have never worried about the amount of Rotational Play.
Wobble could be fairly easily determined by putting the gun in a padded vice on a Bridgeport and using an indicator to measure the amount of angular wobble.
I own many, many revolvers. Many. All different brands, but mostly Colts, Smith and Wesson, and Rugers. I will tell you that every single one of them has a little bit of rotational play when the cylinder is in battery. New ones as well as revolvers that are over 100 years old. There is only one that has absolutely no rotational play, an 'original model' Ruger Vaquero. The reason it has zero rotational play is because the hand is a bit longer than usual. Just by a few thousandths, but it is enough that when the gun goes to battery the 'long' hand takes up any slack between the bolt and the locking slots on the cylinder, locking the cylinder as solid as a rock. What this actually means is that the cylinder is locked at one extreme of its rotational play. If I were to run a range rod down the barrel, I would probably find that to be true.
The bottom line is, revolver cylinders usually exhibit a small amount of rotational play. If you find one without any rotational play, consider yourself lucky. Or, perhaps you had a new cylinder custom line bored to line up perfectly with the chambers. In any event, ALL revolvers have a forcing cone at the rear of the barrel, to catch and align any bullet emerging from the cylinder slightly out of line with the bore.
Most of my revolvers also have a little bit of Endshake. Years ago I had a gunsmith tell me that the Endshake on one of my Colts was very bad. He said it would eventually get worse, the more I shot the revolver. Probably because of recoil battering the frame. I have fired thousands of rounds of Black Powder 45 Colt ammunition through that revolver over the years, and have not noticed the Endshake has grown any.
Aftermarket cylinder base pins such as those offered by Belt Mountain are only a few ten thousandths larger in diameter than a standard cylinder base pin. If the original base pin is loose in the cylinder, or in its holes in the frame, this will help lessen Wobble slightly. It will have no effect on Endhake and very little effect on Rotational Play.
