I recently purchased a 651 from someone on the forum. I finally took it to the range and found the cylinder jams after one or two rounds fired. It appears the casings may be backing out and prevent the cylinder from rotating, although I am guessing it has to do with the cylinder misaligned or backing out or bent yoke. Suggestions or thoughts? Bob

....found this on the web. It worked perfectly for me.

"By stuck, you mean it won't swing out of the frame when you push the cylinder release correct? OK, so you need a thin piece of plastic (I use a scrap of exposed xray material since it is the perfect thickness and tough yet flexible, I cut it into a strip about 1" wide and about 8" long) you can use a business card etc in a pinch. You slide this under the cylinder, between it and the lower frame area. The idea is to depress the cylinder stop back down into the lower frame while you push the cylinder release ad swing the cylinder out. Once you have that done, you can re tighten the ejector rod where it goes into the front of the cylinder. do this by hand, then use a pair of slip pliers with a (I prefer a thin piece of leather) pad around the ejector rod so you don't mar it with the pliers. I modified a pair of pliers to do this with properly, but you can use regular ones if you pad them. Tighten it firmly. That's it. Easy fix. To prevent this, each time you clean the revolver, take an extra minute and make sure it remains tight."

Things to check for:

1. Is extraction hard? switch brand of ammunition.
2. look for burrs around the firing pin hole.
3. check for proper barrel-to-cylinder gap. It should be around 0.006". Too narrow a gap lets firing residue seize the B-C gap.
4. check that extractor rod is tight.