I don't begrudge revolvers that have a little wiggle room as long as (no particular order):
1) when the cylinder is pressed forward, it rests against the frame, not the forcing cone
2) when the cylinder is pressed rearward, it doesn't have excessive B/C gap
3) when the cylinder is pressed forward, it doesn't have excessive headspace (i.e. ignition issues)
4) there is no lateral play, aka no misalignment of the chambers to the bore
If all but number 3 are true, or if you just want to eliminate some of the wiggle, an endshake shim can hold the cylinder to the rear and control headspace and endshake. It DOES, however, open up your B/C gap. Which is really to say that it holds the B/C gap open, so as long as number 2 is true (i.e. zero headspace when pushed forward, and 0.01" or less when pushed rearward), you're groovy with a shim.