JimmyJ there's several different things that could cause the problem you describe..
Give "US" the type of revolver & that may help some..
I'd start by looking at..
1) End Shake Screw, Most farward sideplate screw, It's fit on earlier guns & has a spring loaded detent on later made guns, this limits the farward movement of the yolk on the frame..
2) Yolk endshake & or wear at the tip were the cylinder slides on Yolk/Crane..
3) Wear inside cylinder were yolk rides, alot of heavy magnum use can cause this gouge inside the cylinder that can be smoothed & then the crane stretched or shimmed to make it correct..
More than likely the fix would be an easy one but without more to go one I'm just guessing..
Good Luck, There's alot of great gunsmiths on this forum that may come up with more but I'd be looking at those things first..
Gary/Hk
