Ideally . . . if you want it to be set up correctly, there is a process. I have a '61 Navy in 38sp here so the first step is correcting the arbor length. This particular example is going to need the forcing cone dressed a little so the endshake can be established. The thing to understand is the ratchet is the "stop" for the rearward movement of the cylinder ( now would be a good time to take a headspace measurement). Correcting the arbor length is going to involve a spacer mounted in the arbor hole for the arbor to butt up against. Along with that, the endshake is determined by the cylinder mounted "gas ring" and its proximity to the barrel assy directly under the forcing cone. I like zero endshake with a .002"(smokeless) - .003"( bp) barrel/cylinder gap.
This particular '61 will have the f.c. meeting the cyl before the gas ring meets the bbl assy. For this reason, the f.c. will be dressed enough to allow a zero endshake. Once that happens, the spacer can be installed.
Now, with zero endshake, the f.c. can be further reduced and squared to the appropriate bbl / cyl gap with the wedge driven in.
At this point you have a corrected arbor length, correct bbl/cyl gap and zero endshake. Now you can address the headspace ( by removing recoil shield material if needed).
Headspace clearance was key to making Tame Bill and Jedi Knight's revolvers run!!
Mike