Need a little action tuning help. Knuckling?

[Shadowrider]

Gun is an old model 686-0. Not too high of a round count.

Slicked everything up inside, I do not change angles or alter any geometry on the hammer or trigger. I do a bit of work on the top of the rebound slide but basically just polish what "is there". I also installed a Wilson Combat spring kit and it had a "Carmonized" hammer (by me, about 50% weight reduction).

When I went to set the main spring tension I set the strain screw on the spring and gave it about 1/2 turn. It was popping Federal primers right there. So I add about another 1/4 turn and calculate the amount to remove from the screw and do that. It has fired about 350 rounds in load testing and about 200 more in a match today, plus who knows how many dry fires? Maybe 1000?

It's ran great right up until the last stage of today's match. That's when the hammer decided it no longer wants to fall when the trigger is pulled. So I check the strain screw at the range and it's still tight. I bring it home and in dry fire and it's working fine again. I pulled it apart, complete detail strip, and find nothing wrong. No broken pins, gunk (I had just done this getting it ready for the season), no nothing. I was running Frog lube so I switched to Slip 2000 EWL since I had it on hand.

The trigger didn't seem to be binding, just no hammer fall. The gun's action seems golden. Timing, end shake, all of it seems perfectly functional and in good shape. I've done several guns like this and all have been great. But I can't remember any of the others popping primers as fast as this one did. I don't remember how much I ground off the screw, but all my other guns seemed to have needed more tension on the spring to obtain reliable primer ignition. Does this sound like knuckling?

Edit: I switched lube because frog lube seems to get "sticky" when it's cold.

Edited March 16, 2014 by Shadowrider

[alecmc]

So you were pulling the trigger and the hammer wasn't moving ?

Sounds like your sear wasn't resetting. Either very gunked up or your sear spring is worn out

[Shadowrider]

Yes hammer moved as normal. Releasing the trigger, it would go back down with it. It just wouldn't fall at full trigger travel. Also the gun DOES NOT have an internal trigger stop, it has one on the frame inside of the trigger guard. That ain't it either.

Gun was clean inside. It has basically been detail stripped, cleaned and lubed. Shot one match today and it's now been done again.

[MWP]

Had a similar problem with a 625 recently. After digging around I decided the pin inside the rebound slide was backward. There was an end that was somewhat rounded, and an end that was cut off at 90 degrees. The square end was toward the trigger, binding up on an edge inside the rebound slide. I flipped the pin around.

That was my issue, might be worth checking out.

[RePete]

Do you have a factory trigger stop in the gun (behind the trigger) or the rod inside the rebound spring? There is a slot behind the trigger in the trigger well.

If the retaining screw (accessible from under the sideplate) gets loose, the stop with impede rearward trigger travel.

[pskys2]

Knuckling is when the mainspring doesn't have enough arch. The hammer will reach a point and then the trigger gets real hard and may not go far enough to drop the hammer.

Can you hold the trigger back and rotate the hammer by hand freely?

Wonder if you have a cracked hammer from the dremel mites eating into a critical area.

[Shadowrider]

Do you have a factory trigger stop in the gun (behind the trigger) or the rod inside the rebound spring? There is a slot behind the trigger in the trigger well.

If the retaining screw (accessible from under the sideplate) gets loose, the stop with impede rearward trigger travel.

Behind the trigger. Stop is tight and does NOT impede travel. As a matter of fact it's not much of a stop. Maybe for SA, but DA breaks a good bit before the stop engages the trigger. All the custom stops I've ever seen installed on triggers have been much tighter.

Knuckling is when the mainspring doesn't have enough arch. The hammer will reach a point and then the trigger gets real hard and may not go far enough to drop the hammer.

Can you hold the trigger back and rotate the hammer by hand freely?

Wonder if you have a cracked hammer from the dremel mites eating into a critical area.

Yes, hammer is free as a bird with trigger pulled. Don't think it could be cracked, I was real gentle with it since it's an old school forged hammer and I made sure not to let it get hot when I cut it.

It's working in dryfire and always has before. The only thing done to the gun since the trigger work was that I just I sent the cylinder to TK Custom and had them cut it for moons. It's not binding, getting light strikes, etc. so I really can't see how that would be an issue. I think it's just coincidence because the cylinder work seems perfect. I can't tell any difference at all except when loading.

[Carmoney]

Edit: I switched lube because frog lube seems to get "sticky" when it's cold.

I am going to use this as an opportunity to recommend that revolver shooters lubricate with a small amount of synthetic motor oil only. No greases or heavy viscosity oils are recommended.

That said, I don't think you're dealing with a lubrication issue. Sounds like a strange situation.

[pskys2]

Sounds an awful lot like you have a broken Trigger Pin, They bend easily, but but see if it has any wiggle to it. I had one that broke but was still in the recess so the first time I looked at it it was there. As soon as I gently wiggled it I knew what the issue was.

[Shadowrider]

Sounds an awful lot like you have a broken Trigger Pin, They bend easily, but but see if it has any wiggle to it. I had one that broke but was still in the recess so the first time I looked at it it was there. As soon as I gently wiggled it I knew what the issue was.

That would sure do it wouldn't it?

I just had the thing completely tore down and it didn't fall out when I blasted it with brake cleaner. If it happens again I'll take the sideplate off yet again and check it better, so far in dry fire it's perfect.

[Shadowrider]

RePeat at post #5 nailed it. It in fact was a loose trigger stop.

When I had it apart I couldn't move it by hand in the frame and just took for granted that it was tight. Like I posted above I had it all cleaned out and re-lubed, etc. and I've been dry firing it through the week without any problem. Went to the range to do some load testing today and fired one shot and we were locked up again. Disassembly at the range revealed the the stop had rotated out and was blocking the trigger. I checked it's screw (that appeared to be seated) and find it loose, just not backed out at all looking. Doh! So I fiddled with it, got it adjusted pretty decent and tightened down. All is well in vintage L Frame land again...