19-3 cocking problem

[les45]

I just got a steal on a really nice 19-3 with 6" barrel. The only problem (and I knew it when I bought it) is that it locks up when trying to cock the hammer in single action mode. By that, I mean that you can only pull it half way back and it stops. If I drop the hammer back down, it will work as normal in double action mode with just a slight heaviness in the last half of the pull (not quite as smooth as normal S&W double action). It does this most of the time, but not all of the time. I would like to troubleshoot this myself before I give up and take it to a gunsmith. I haven't taken the sideplate off yet, so I haven't seen if any of the internal parts are worn or broken.
Any guesses on where to start or what parts are most likely to be causing this problem?

 

[Alk8944]

First, tighten the strain screw. Sounds like it is loose, which lets the arch out of the mainspring making it longer. What happens is the effectively lenghtened spring stubs under the lower arch of the hammer blocking it.

If this doen't fix it let us know and we'll give it some more thought. Betcha it does though.

BTW, the strain screw is the one in the lower front of the forestrap of the grip frame. If the gun has target stocks you will have to take them off to get to the screw.

 

[les45]

First, tighten the strain screw. Sounds like it is loose, which lets the arch out of the mainspring making it longer. What happens is the effectively lenghtened spring stubs under the lower arch of the hammer blocking it.

If this doen't fix it let us know and we'll give it some more thought. Betcha it does though.

BTW, the strain screw is the one in the lower front of the forestrap of the grip frame. If the gun has target stocks you will have to take them off to get to the screw.

Thanks, Alk, but the strain screw was bottomed out as tight as it would go. I finally took the sideplate off and all the parts on the inside look like brand new. No wear on anything. The bore on this gun is near mint so it doesn't look like it has been shot much at all. The movement of all the internal parts, including the hand, appears to be normal until the hand hits the cylinder lug. The one thing I noticed is that the cylinder seems to be binding when it is released. That seems to be what is causing the reluctance of the follow through when cocking for single action. The stop is releasing as it should, but when you pull back on the hammer slightly, the cylinder does not spin freely like it should. There is a gap on both ends, the cylinder looks squared to the frame and there are no drag marks on anything. Any other thoughts with that info?