I also have a model 60 that has just the slightest amount of rotational play and it is not a problem. If you say the gun shoots good then I wouldn't worry about it. One real good way to check timing is to put snap caps in all the cylinders and cover all the faces of the snap caps with a little piece of masking tape and dry fire to your hearts content. Check the tape after a dryfiring and see how well it punches the center of the tape out and the hits should be in the center. The masking tape will come right off except for the little dot the firing pin punches out. Peel it off with the point of your pocketknife. With the trigger pulled and tension back on the trigger also check and see how tight the cylinder is locked up on the fireing position. I think you will see a significant tighter lockup than checking slack on the cylinder in the released position. This works for me.
Enjoy that model 60.
