I was watching the Larry Potterfield video where he demonstrates how to correct cylinder end shake. He is shown putting the extractor rod (i think thats right) in a vice and turning the cylinder to unscrew it from the rod. I couldn't tell from the video but if one where to use the vise as shown and you were facing the cylinder would you turn it clockwise or counter clockwise. I'm thinking counter clockwise to loosen.

Ok, I just found another video and it actually shows him turning it clockwise to remove the cylinder.

Make sure you put some empty cartridge brass in the cylinder before you start to turn....

Older S&W's were right hand threads (counter clockwise to loosen) but many years ago they switched them to left hand threads (clockwise to loosen). You didn't state what you are working on, but odds are clockwise to loosen.

Thanks jepp2, i thinking about shimming a model 13-3.

I shimmed a M-66 and it worked out just fine.

I didn't have a yoke facing reamer so I kind of improvised. I drilled a hole through a piece of wood on my drill press, just larger than the yoke OD and then I could rotate it against different grits of sandpaper. Cleaned it up just fine.