Check to see that the ejector rod is not loose. Its a somewhat common problem, and if it is, it will eventually tie the gun up until its been addressed.
Regardless, I would still put about half a drop of LocTite on it, as its one of the few things that will tie a revolver up. Dont get crazy with it, or the LocTite itself will give you troubles.
Another spot to check is under the extractor star. If there is the least little bit of fouling under it, it too can give you troubles. It can make the cylinder difficult to open and close and also make it difficult to cycle. You'd be amazed at how little junk needs be under there for it to be a problem too. The main culprit here, is not reloading the gun, or dumping the empties properly. Revolvers should always have the empties dumped "muzzle up".
Zeitgeist - The movie
Zeitgeist - Addendum