625 Timing Issues

[kmc]

I have a JM 625-8 that has only several hundred rounds through it. I've gone through the gun, chamfering the cylinder, adding a Miculek spring kit, bobbing the hammer, adding different cylinder release/grips, and did a trigger job following Jerry's video. It was the first time with a revolver and fun to do. I've had to do the normal loading with the gun done in this manner--Federal primers, fully seated. The trigger ended up very nice though I've been plagued by a recurring problem. When I shoot fast, the timing jumps off and I'll only hit 3-4 rounds in some 6-round trigger pulls. If you watch the gun and pull the trigger fast, you can see the cylinder occasionally seems to stop where it shouldn't when the hammer drops--I cannot tell if its going too far or not far enough. When I shoot normally, it shoots without fail...though I am sure I'm not short-stroking. I've tried several things to solve the problem, all to no avail.

At first I thought it was related to a slightly bent cylinder stop spring that wasn't stopping the cylinder properly. I replaced the spring and eventually replaced the stop without any change.

Most recently I thought it was related to the cylinder itself--the timing notches were a bit messy--I had cleaned them up a bit and was afraid I screwed it up. I swapped cylinders with another JM gun and I couldn't make it fail in a short test. As a result, I ordered a new cylinder for the gun and just got done trying to get it in the gun and the problem did NOT go away :-( In fact, I found a second issue...allow me to diverge a bit. Do cylinders require some sort of fitting? I found that the cylinder seems to fit and lock up fine but I've found the hammer won't always drop in double-action without *really* squeezing the trigger. Upon closer examination, it looks like the hand is not moving enough up through the ratchet to release the hammer, though its very close. In fact, a good indicator is that the hand will no longer go high enough for the hammer/trigger to engage in the single action "notch"--they'll touch but won't go far enough to lock the trigger back. My other cylinder allows this to happen just fine. I don't want to touch the ratchet for fear of introducing another timing issue. What gives?

Now back to the original problem. When I could make the trigger work well enough with the new cylinder to test the timing, I can see that I've still got the same issue going on. The hammer is falling when the cylinder is not in the right position. For some reason, I've been suspicious of the hand and hand spring for some time. I did have them apart during the trigger job. Although it does have spring tension, it doesn't seem to have a lot of it. I'm wondering if the hand somehow floats when I'm shooting fast and occasionally doesn't get a good turn on the ratchet. Could this be a problem?

Any ideas on what else could be at fault? I was careful when I did the trigger work and don't think I overdid it and hawged out some parts too far...but at this point I won't rule anything out. I'm going to have to replace parts one at a time until it corrects itself.

Fortunately, I've got the expensive swap (cylinder) out of the way but unfortunately, it didn't seem to resolve it... :-(

[4mike]

oversize or factory cylinder stop ?

what lube you use at cylinder stop ?

[Carmoney]

I would start by installing your original extractor in your new cylinder. That should eliminate the binding you describe.

Next, I would make sure the hand torsion spring is installed correctly, and then use a small file (or maybe an emery board) to very gently clean up the window where the hand comes through. Did I mention gently? You're only looking to remove burrs, not change any dimensions.

[kmc]

oversize or factory cylinder stop ?

what lube you use at cylinder stop ?

Factory cylinder stop. Lube is Militec, though not much.

[kmc]

I would start by installing your original extractor in your new cylinder. That should eliminate the binding you describe.

Next, I would make sure the hand torsion spring is installed correctly, and then use a small file (or maybe an emery board) to very gently clean up the window where the hand comes through. Did I mention gently? You're only looking to remove burrs, not change any dimensions.

I will give this a try tonight, starting with my extractor. I did notice there were burrs on the window last night and very gently took them off yesterday. The hand seems to have a place (near full extension) where I don't get much spring tension. If I help it to close a bit, it seems to get the tension right back. Is this normal? I *think* I've got the hand spring in there correctly but will confirm tonight. Do you happen to have a good reference I could compare against?

[lugnut]

Do cylinders require some sort of fitting? I found that the cylinder seems to fit and lock up fine but I've found the hammer won't always drop in double-action without *really* squeezing the trigger. Upon closer examination, it looks like the hand is not moving enough up through the ratchet to release the hammer, though its very close. In fact, a good indicator is that the hand will no longer go high enough for the hammer/trigger to engage in the single action "notch"--they'll touch but won't go far enough to lock the trigger back. My other cylinder allows this to happen just fine. I don't want to touch the ratchet for fear of introducing another timing issue. What gives?

My brand new 627's timing was so early I had the same problem. It would take considerable extra trigger pull to drop the hammer in DA. In my case it was the same in every chamber. I worked the hand ever so gently. I got it all nice except for one stubborn chamber. Once I determined the knuckle that was causing this hang up I little work made it all good.

I'd have to imagine that the timing is determined mostly by the hand/knuckles/extractor but it seems like it's dependent on the cylinder as well.

You may have got yourself in a mess as it seems like your timing is either to late and/or early. You might want to send it to someone who knows what they're doing at this point... unless you have lots of time and money for spare parts.

Edited October 10, 2012 by lugnut

[Carmoney]

oversize or factory cylinder stop ?

what lube you use at cylinder stop ?

Factory cylinder stop. Lube is Militec, though not much.

Shit, I've never lubed a cylinder stop. I don't think it's a lube issue. In fact, I don't even think it's a cylinder stop issue. Then again, who knows?

[toothguy]

I have a JM 625-8 that has only several hundred rounds through it. I've gone through the gun, chamfering the cylinder, adding a Miculek spring kit, bobbing the hammer, adding different cylinder release/grips, and did a trigger job following Jerry's video. It was the first time with a revolver and fun to do. I've had to do the normal loading with the gun done in this manner--Federal primers, fully seated. The trigger ended up very nice though I've been plagued by a recurring problem. When I shoot fast, the timing jumps off and I'll only hit 3-4 rounds in some 6-round trigger pulls. If you watch the gun and pull the trigger fast, you can see the cylinder occasionally seems to stop where it shouldn't when the hammer drops--I cannot tell if its going too far or not far enough. When I shoot normally, it shoots without fail...though I am sure I'm not short-stroking. I've tried several things to solve the problem, all to no avail.

At first I thought it was related to a slightly bent cylinder stop spring that wasn't stopping the cylinder properly. I replaced the spring and eventually replaced the stop without any change.

Most recently I thought it was related to the cylinder itself--the timing notches were a bit messy--I had cleaned them up a bit and was afraid I screwed it up. I swapped cylinders with another JM gun and I couldn't make it fail in a short test. As a result, I ordered a new cylinder for the gun and just got done trying to get it in the gun and the problem did NOT go away :-( In fact, I found a second issue...allow me to diverge a bit. Do cylinders require some sort of fitting? I found that the cylinder seems to fit and lock up fine but I've found the hammer won't always drop in double-action without *really* squeezing the trigger. Upon closer examination, it looks like the hand is not moving enough up through the ratchet to release the hammer, though its very close. In fact, a good indicator is that the hand will no longer go high enough for the hammer/trigger to engage in the single action "notch"--they'll touch but won't go far enough to lock the trigger back. My other cylinder allows this to happen just fine. I don't want to touch the ratchet for fear of introducing another timing issue. What gives?

Now back to the original problem. When I could make the trigger work well enough with the new cylinder to test the timing, I can see that I've still got the same issue going on. The hammer is falling when the cylinder is not in the right position. For some reason, I've been suspicious of the hand and hand spring for some time. I did have them apart during the trigger job. Although it does have spring tension, it doesn't seem to have a lot of it. I'm wondering if the hand somehow floats when I'm shooting fast and occasionally doesn't get a good turn on the ratchet. Could this be a problem?

Any ideas on what else could be at fault? I was careful when I did the trigger work and don't think I overdid it and hawged out some parts too far...but at this point I won't rule anything out. I'm going to have to replace parts one at a time until it corrects itself.

Fortunately, I've got the expensive swap (cylinder) out of the way but unfortunately, it didn't seem to resolve it... :-(

Order a new hand and spring from Brownells and fit to the cylinder you want to use. Fit by carefully filing the inside top tip of the hand that meets the ratchet this is trial and error one or two strokes with the diamond file and install. I like to get it close then polish the rest of the way. I leave it just a touch to advanced and shoot it in. The hand is hard steel but the ratchets are not. don't touch the ratchets. I get cheap diamond files from Harbor Freight that work great. The hand and spring are cheap if this was not the problem it's nice to have a spare anyway.

Edited October 11, 2012 by toothguy

[kmc]

I would start by installing your original extractor in your new cylinder. That should eliminate the binding you describe.

I swapped extractors and sure enough, the cylinder works fine and now I'm be back to the original timing problem. This just tells me that a new cylinder must in fact require fitting. I presume all the fitting would be done on the *hand*, never on the ratchet?

Just curious on this. I'm going to go with my original cylinder while I try to fix the original problem. I didn't have time to pull the hand last night but now off to order one and a spring from Brownells...

[Toolguy]

It's a very touchy and difficult job to file all the ratchets to be alike. There is a high probability of ruining them in the process. Assuming the ratchets are alike to begin with, it is far simpler to fit the hand to the ratchets. There you are working with one cheap and easily replaceable part. Sometimes all the ratchets are not alike as in the case of guns made during the Bangor Punta and Lear Siegler days. In that case, you would fit the hand to the lowest ratchets, then file the one or two high ratchets to work with that hand. I have learned from experience not to file on the ratchets unless all other options have been tried. Experience is what you get right after you need it.

[toothguy]

Toolguy is a master of adjusting the unadjustable. Let us know how it goes

[4mike]

It's a very touchy and difficult job to file all the ratchets to be alike. .......

I use pivot into the cylinder chamber with 3/8" OD ball bearings as support for correct angle of file

Edited October 16, 2012 by 4mike

[earplug]

I have bent the spring that works the DA sear when working on the hammer.

This gave me inconsistent hammer action with the trigger.

I might not be understanding the problem, but this is a simple mistake to make. And easy to check.

[kmc]

With a little prompting and now that S&W finally got me parts, I got back to messing with my 625. Where I left off is I'm suspicious the hand is not properly riding the ratchet and I'm about to swap the torsion spring to see if that helps. The pictures below are from my 625-8 JM model. I did have this torsion spring out once before--and I'm about to swap in a new one. I recall it being a real bear to change and I cannot see where I could have put it back together wrong. Just the same, is there anything bad about the pics below?

Correction: After taking the hand out...I don't think I ever actually removed the pinned spring before. Previously, I had just took the hand out and put it back in. This pin isn't falling out--gonna have to get me a pretty narrow push punch to get this pin out.

Edited October 25, 2012 by kmc

[snertley]

I think it just needs more beer!

[kmc]

With a little prompting and now that S&W finally got me parts, I got back to messing with my 625. Where I left off is I'm suspicious the hand is not properly riding the ratchet and I'm about to swap the torsion spring to see if that helps. The pictures below are from my 625-8 JM model. I did have this torsion spring out once before--and I'm about to swap in a new one. I recall it being a real bear to change and I cannot see where I could have put it back together wrong. Just the same, is there anything bad about the pics below?

Correction: After taking the hand out...I don't think I ever actually removed the pinned spring before. Previously, I had just took the hand out and put it back in. This pin isn't falling out--gonna have to get me a pretty narrow push punch to get this pin out.

Wow, I have no clue how to get the spring pin out of the trigger. It seems to be solid and no small matter to remove even with the right size punch. I'm going to try swapping in another hand for now.

[lugnut]

I'd be shocked if you problem is a bad hand spring.

[kmc]

Well, I gave up on swapping the spring but did swap in a new factory JM hand. There was a bit of difference because I had relieved the hand edge per the trigger job video. I put it back together with the replacement hand without any fitting whatsoever. Although it worked without fitting, it unfortunately demonstrated the same results. If I shoot slowly, all is well. If I shoot quickly, the timing eventually whacks out--its hard to see but the cylinder seems to rotate only part way to the next stop which throws the timing is off. Use of the new cylinder and original ejector makes no difference. New cylinder and new ejector also exhibit problem but it will not fire single action (hand won't pass the ratchet far enough to allow hammer lockup).

Thoughts please?

[kmc]

I have bent the spring that works the DA sear when working on the hammer.

This gave me inconsistent hammer action with the trigger.

I might not be understanding the problem, but this is a simple mistake to make. And easy to check.

Please tell me more. What am I looking for? And how did you fix it?

[earplug]

Order a new spring. Its the same spring that works the cylinder bolt plunger.

I don't know the factory length, but you have to cut it to fit the hammer DA sear.

I put it on a piece of thin wire when I cut the spring to keep it from bending or flying into space.

I have bent the spring that works the DA sear when working on the hammer.

This gave me inconsistent hammer action with the trigger.

I might not be understanding the problem, but this is a simple mistake to make. And easy to check.

Please tell me more. What am I looking for? And how did you fix it?

[BlueOvalBandit]

Brownells has the correct spring for MIM hammers, no cutting needed.

http://www.brownells.com/handgun-parts/trigger-group-parts/sear-parts/sear-springs/sear-spring-mim-hammer-sear-spring-mim-hammer-sku940-000-508-14712-34189.aspx

[toothguy]

I have bent the spring that works the DA sear when working on the hammer.

This gave me inconsistent hammer action with the trigger.

I might not be understanding the problem, but this is a simple mistake to make. And easy to check.

Please tell me more. What am I looking for? And how did you fix it?

I wish I had it in my hands to look at it. It's probably something simple. Is there anyone you know that could help you with it, another shooter perhaps?

[BlueOvalBandit]

Your looking at the spring behind the black DA sear, its pretty easy to bend

Exploded

Use a small flat screwdriver or exacto blade to get the spring compressed when reassembling.

[4mike]

........ If I shoot slowly, all is well. If I shoot quickly, the timing eventually whacks out--its hard to see but the cylinder seems to rotate only part way to the next stop which throws the timing is off.........

Try numbered chambers by red fat alcohol pencil, you will find if cylinder rotate only part of 60° or if it skip aretation of cylinder stop

Edited October 26, 2012 by 4mike