I recently purchased a used stainless Smith & Wesson md. 66 from SOG and it has got a little more previous use than I expected.  My question is regarding the yoke, or crane where it meets the frame.  Just looking at it, it appears to be an excellent, tight fit.  If I apply moderate pressure to the cylinder, a small gap is evident (I could perhaps fit 1 or 2 cigarette papers in it).  I don't get the same result on my 38 spcl Md 10 (blued).  Is this normal wear?  I don't have a way to measure the gap, but it is easily noticeable.  any thoughts?  Is it safe?  or maybe one to trade in on something newer?

Yes, this is not unusual. S&W may very well fix it for free due to liability concerns, IMO.

As long as the cylinder times up ok & there's no splitting of lead at the forcing cone gap, I'd shoot it.

Good luck.

Check the Forcing Cone for any hair line cracks, and use auto feeler guages to check the cylinder gap. The M66 can have problems do to 357 mag use. This is a fine gun, but check it out and go over to the S&W board and check that gap measurement with their factory rep.

Quoted: I recently purchased a used stainless Smith & Wesson md. 66 from SOG and it has got a little more previous use than I expected.  My question is regarding the yoke, or crane where it meets the frame.  Just looking at it, it appears to be an excellent, tight fit.  If I apply moderate pressure to the cylinder, a small gap is evident (I could perhaps fit 1 or 2 cigarette papers in it).  I don't get the same result on my 38 spcl Md 10 (blued).  Is this normal wear?  I don't have a way to measure the gap, but it is easily noticeable.  any thoughts?  Is it safe?  or maybe one to trade in on something newer?

I just looked at my model 66. Since this assembly must pivot, there must be some play between the two and 1 or 2 cigarette papers isn't a lot, I'd say that's about where mine is.

The thing to watch with Model 66 cylinders is difficulty removing brass after firing full house .357 loads.

If your gun has been abused, there will be case bulging under the notches on the cylinder, making spent cases difficult to extract.

A new cylinder costs about $120 and another $50 for labor.

I haven't found S&W customer service anything to rave about, so getting them to do service work outside warranty can be a challenge.

The Model 66 is a fine gun that greatly benefits from trigger work and responds real well to a trigger job.

It will eat a steady diet of .38 Spl +p+ with no problems. I've heard from other about problems after lots of max loaded .357.