K Frame locks up in DA

[m1gunner]

My early model 19 started locking up in DA shooting today. Have had it several years and never any problems with it.

If I have my finger a little high on the trigger and try to shoot in DA, it locks up tighter than a tick. It matters not how hard the trigger is pulled, the cylinder doesn't even start to move.

If I have my finger toward the tip of the trigger, it is fine.

No problems in SA shooting.

No recent changes, nothing looks out of place inder the side plate.

I haven't seen this mentioned, what is it doing?

 

[Big Cholla]

m1Gunner: Diagnosing is just a guess without the handgun on my bench. But I suspect that something is cramping up in the DA mode. My first move would be to take the side plate off again and inspect every part that moves in the DA mode with a good magnifying glass and compare to known good parts. Then reassemble all except the side plate. Support the handgun on its side to allow you to slowly pull the trigger thru in DA. Do this both with the cylinder installed and with it out of the frame. You can pull the trigger thru with the cylinder out of the gun by holding to the rear the the cylinder latch. Watch the pivot pin the trigger rotates around. See any lateral movement in the pin itself? Do the same for the hammer pivot pin. Looking further, take the hammer out and then the trigger. Look at the full length of the trigger and hammer pivot pins for a crack that is 1/2 or more thru the pin. Find that crack and the handgun has to go back to S&W.

If the trigger/hammer pivot pins are ok, watch the hand for rotation movement. Make sure the cylinder stop spring is ok and not broken.

Eliminate the "good' parts from the equation and usually you will find the problem. .............. Big Cholla

 

[m1gunner]

Thanks for the reply.

The Hammer pin and trigger pin aren't cracked, but both show some visable wear.

What appeared to be happening is the cylinder stop was jumping off the trigger cam when the trigger was pulled just the right way.

This confirmes what I saw, the hammer would start back, then nothing would move.

I swapped in a spare trigger, and it quit locking up. The original trigger looked fine, no cam surface wear to speak of.

With the wear showing on the trigger pin, does this indicate a trip back to S&W for installation of new hammer and trigger pivot pins?

 

[Big Cholla]

Probably not. The replacement trigger took care of the problem so don't sweat it. Good for you in making the effort to understand your handgun. If you really get into tuning S&W revolvers I highly recommend you get a copy of Jerry Kuhnhausen's "The S&W Revolver A Shop Manual" in book or DVD form. Jerry's work is very complete and very understandable. .... Big Cholla