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cylinder stop catching cylinder notch & locking up


alecmc
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guys, dabbling around with another n-frame trying some amaturish trigger work and learning.. having an issue with the trigger locking up, happens mostly in rapid fire.

It looks to me like the cylinder stop isnt coming down all the way, or fast enough and is catching the cylnder notch and freezing everything up in place.

before I start trying to remedy I was looking for some insight on what it might be and what to do to resolve this.

thanks.

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what it looks like locked, def. getting hung up with cylinder stop

8702048753_76df328473_b.jpg

on the face of the trigger that contacts the cylinder stop to bring it downward has a protruding nubb, can this by stoned down a little bit ? Or do I need to bring the cylinder stop closer toward it so it comes down farther ?

8702048259_edd9bd5130_c.jpg

Edited by alecmc
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having an issue with the trigger locking up, happens mostly in rapid fire.

Are you sure you're not short-stroking?

Positive, I made effort to make sure I wasn't to cross off the list, it happens mostly in rapid fire, but will happen in a medium paced shot cadence as well

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Hmmm, .006 worth of trigger pivot shims on the side plate side seemed to help a ton... trigger felt a little slop.... dont know why? Pulled the trigger as fast as i could for a good few minutes worth with no problems..

Hopefully live fire doesnt bring any issues..

thoughts?

Edited by alecmc
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You need that nub on there - do not make it smaller, that will make the problem worse. You can take out the stop and file the front part of the pivot pin slot to let the stop go closer to the trigger. That will advance the timing of the cylinder stop.

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Thanks tool guy, I'll keep that in mind.

Though, i'm a little confused to why it seems to be running ok in dry fire right now... I've been yanking on the trigger for 10 minutes now and it hasnt jammed up.

I've got 3 .002 trigger pivot shims on top of the trigger and its not doing it anymore... Could the trigger have been cocking a little bit to the side and just not engaging properly?

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Does the cylinder stop have a corresponding "groove" in it? I've never seen a "nub" like that on the trigger, though I'll admit I've tuned mostly earlier model guns rather than late models. Only done a couple of late MIM guns.

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Does the cylinder stop have a corresponding "groove" in it? I've never seen a "nub" like that on the trigger, though I'll admit I've tuned mostly earlier model guns rather than late models. Only done a couple of late MIM guns.

No , it does not.

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The nub is a mim trigger thing. The idea is to reduce friction by having a smaller surface area. The nub is at the point where a regular trigger would be, the material around it is rebated. I have never seen this problem caused by a trigger having side play.

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The nub is a mim trigger thing. The idea is to reduce friction by having a smaller surface area. The nub is at the point where a regular trigger would be, the material around it is rebated. I have never seen this problem caused by a trigger having side play.

Interesting. I saw a rebound slide that had been modded similarly. I've only done 2 625JMs and the only other MIM gun I've played with was my J frame. None of those have that.

What piqued my interest was that .006" of shim seems to have fixed it. I thought that maybe if there were a corresponding groove that the change in centerline would make the cylinder stop's arc of motion longer. It seems that the two contact surfaces aren't parallel or the pin for the cylinder stop is out of square possibly? But your suggestion of filing the pin slot is probably the easiest fix.

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I'm stumped on why the shims seem to be fixing it for now, I'll give it another round of a variety of dry fire, if I get problems I'll file out the pivot slot for the cylinder stop to bring it closer to the trigger.

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If I'm understanding you correctly, the problem is that the cylinder stop drops at the beginning of the trigger pull, but then pops back up into the cylinder stop notch before the cylinder indexes around far enough to move the notch out of the way, locking everything tight.

I've seen that issue multiple times. Assuming you have not created the problem by filing down the "nub" or changing the dimensions of the cylinder stop bevel, you probably need to replace the hand. A hand with larger dimensions will get the cylinder moving more quickly in the trigger pull sequence, and allow the notch to clear before the cylinder stop pops up.

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Look at the trigger where the pivot pin goes thru. It's cut out to allow the cylinder stop to drop into the recess. If the trigger moves moves sideways (usually towards the sideplate) the cylinder stop can hit the trigger instead of moving down into the recess.

Trigger is trying to pull the cylinder stop down but the stop is hitting on the trigger and can't move down. Ties up the trigger big time just into the trigger pull.

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Look at the trigger where the pivot pin goes thru. It's cut out to allow the cylinder stop to drop into the recess. If the trigger moves moves sideways (usually towards the sideplate) the cylinder stop can hit the trigger instead of moving down into the recess.

Trigger is trying to pull the cylinder stop down but the stop is hitting on the trigger and can't move down. Ties up the trigger big time just into the trigger pull.

Makes sense, I haven't been able to replicate it again, but if it starts again I have alot if good advice to go through , thanks again guys

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Still good to go so far.

I matt griffined the the trigger for a good 5 minutes until I thought my finger was going to fall off, no issues.

Took the shims out, side plate back on.... Jammed up, shims back in.... no problems.... Dont know why or how, but hey - it's working.

Shooting a steel match with it tomorrow, hopefully she runs 100%

Edited by alecmc
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Still good to go so far.

I matt griffined the the trigger for a good 5 minutes until I thought my finger was going to fall off, no issues.

Took the shims out, side plate back on.... Jammed up, shims back in.... no problems.... Dont know why or how, but hey - it's working.

Shooting a steel match with it tomorrow, hopefully she runs 100%

My 617 would the same thing. Drove me nuts. Trigger would lock up coming into the first plate or arbitrarily during a run. Really annoying. Remove the sideplate and slide the trigger slightly up on it's pivot and it's easy to duplicate the lock-up. Locks up the trigger as the cylinder stop moves down and hits the the trigger. Seems to be a tolereance stacking thing. Shimming the trigger (shims on the sideplate side) fixed mine.

Different (fitting) issue than when the cylinder stop slides off the trigger prematurely (easy to do if you stone the MIM triggers' "little nub" too much/incorrectly) and moves back up into the cylinder notch before the hand has moved the cylinder.

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To expand on what Tom is describing, maybe if you bevel the edge that the cylinder stop catches on when the trigger is moved toward the side plate will help prevent it from happening. Sometimes pictures are just easier so..

Trigger1.jpg

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Thanks guys, I'll have to check that part of the trigger for any rubb marks if it's making contact next time I mess with it.

Today didnt go as so great @ the steel match.... on the first stage I had some issues with it locking up, thought it'd be a good idea to swap out triggers, I had found one earlier that morning in a spare parts box and brought it along. As soon as I took the side plate off the rebound spring decided it'd be a good idea to check out the scenery and went flying off into the distance. I stupidly did not have a spare and put me out of service for the day.

once I got home I fitted the new trigger, and then lost the little cylinder catch spring somewhere on the basement floor, never to be found... Again, no extra!

spent some $$$ @ brownells and ordered like 5 spare pieces of everything to keep at home and in range bag.

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Gregg K said:

To expand on what Tom is describing, maybe if you bevel the edge that the cylinder stop catches on when the trigger is moved toward the side plate will help prevent it from happening. Sometimes pictures are just easier so..

Trigger1.jpg

+1 That "was" the edge the cylinder stop can catch on.

and to clarify , my endshake is fine for those thinking " binding up while shooting " thing... Went through that, and double checked.

:-)

IF it's the stop catching on the trigger it's at the VERY begining of the trigger pull. Issues involving cylinder rotataion occur later in the pull after the trigger has been pulled far enough for the hand to engage the rachet. .

Edited by Tom E
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