So I recently picked up a S&W Model 19-3 and I absolutely love the gun. It does, however, seem to have a couple of minor issues.

#1
The cylinder is a bit difficult to open. It seems like the end of the ejector gets hung up on the locking bolt. In order to open it I need to pull the cylinder rearward slightly so that the locking bolt is cleared. When the gun was sold to me this was declared to be a problem that wasn't necessarily worth remedying due to the risk of messing something up. I suppose I can live with it.

#2
On a somewhat related note (and finally getting to the main point of this post), there does seem to be an excessive amount of cylinder endshake. On the one hand, it is this endshake that is apparently making it possible to open the cylinder at all, but at between 10-11 thousandths of an inch (0.010-0.011") it seems a bit much. I know that I could pretty easily install a cylinder bushing or two to correct the endshake, but I'm concerned that my b/c gap would end up being too big (currently approx 0.005-0.006").

The timing on the gun is pretty tight and it shoots like a dream. I'm just not sure what if anything I should do.

I assume you have checked the ejector rod to make sure it's not backed out?

Excellent point that I should have addressed. Yes, I have actually taken the cylinder apart to check for any abnormalities and clean the crane/yoke (which was swimming in a rather viscous grease). The ejector is fully seated/screwed in.

I wonder if the ejector rod was replaced at some point and not properly fitted (that is, it's just a bit too long)?

Are you able to push the thumb latch full forward. If something is obstructing its movement, the cylinder pin will not push the latch out of the ejector rod recess.

Close cylinder & look at gap between cyl. & cone. If it is too close it may have been overcharged & moved cyl.--Factory can fix this before it screws the gun up.--Ejector rod loose will cause same problem.--JACK

I don't think that correcting your endshake will mess up your b/c gap. I've experienced endshake on two of my revolvers, a Model 27 and a Highway Patrolman. In my guns the endshake was so pronounced that the cylinder would bind against the forcing cone once the gun heated up after a few rounds were fired. The endshake also seemed to affect the guns' accuracy. In both cases, installing a cylinder shim resolved the issue without increasing the barrel/cylinder gap. Performance improved markedly after this inexpensive fix. My 27, in particular, went from a mediocre shooter to an absolute tack driver.

That all said, I'm not sure that I'd worry about the endshake so long as there's no binding and the gun shoots accurately for you. If it ain't broke, don't fix it! The binding ejector rod is another story, however. I'd get that checked out and repaired.

If your revolver has .010-011" end-shake that isn't just "a bit much" it is a LOT TOO MUCH. This by itself can be the reason that the cylinder will not open, but will if you push the cylinder to the rear. End-shake should not exceed .002.

The problem is the bolt can only push the center pin flush with the face of the breech. If the cylinder can move forward .010" that is aprox. that amount that the front end of the center pin will be short of the end of the extractor rod. When you pull the cylinder back the center pin stays put and the extractor rod moves back with the cylinder pulling the end of the extractor rod flush with the center pin and allowing the cylinder to unlatch.

When the gun is fired the cylinder moves, first forward from the firing pin strike, then backward from gas pressure against the breech, then forward again against the end of the yoke barrel. This is what results in some battering of the breech from the extractor ratchet, and to the end of the yoke barrel. Collectively this repeated battering is what causes end shake. The greater the end shake the more forcefully the cylinder strikes the breech and yoke barrel so the more end shake there is the faster it progresses.

Forget about checking barrel-cylinder gap with the cylinder forward, it doesn't mean anything. The functional B-C gap is what it is with the cylinder pulled all the way against the breech. End shake has to be addressed and reduced to something less than .002", then the B-C gap by setting the barrel back a turn.

The greatest probability if your gun has a B-C gap as large as .016 when the cylinder is pulled back, odds are that when the gun had started to get a lot of end shake the cylinder began to drag on the end of the barrel. Someone, who had no idea what he was doing, saw the drag as the problem and filed the barrel breech to re-establish the B-C gap instead of fixing the end shake which would have moved the cylinder away from the barrel. "Fixed" the wrong problem, and by doing so did a lot of damage to the gun.

What should you do? Unless there is a REAL gunsmith in your area that can be trusted with revolvers, and there are very few of them, I suggest you send it back to S&W for repair. Not only can they do the work right, they will probably do it for less. Unfortunately there are shipping costs. I would have your LGS ship it for you, it will cost a lot less than shipping it yourself.

__________________
Gunsmithing since 1961

As far as I can tell the thumb has full range of motion.

I believe Alk8944's explanation sounds the most likely (and also was a clear, concise assessment -- thanks for that). While I don't see any obvious evidence of barrel filing (not that I would), that seems to make sense.

Any recommendations for a good smith near Boston?

Actually, I suppose geography is on my side; any reason not to send it to S&W?