Hammer Block impedding trigger return

[a468bu]

I have a 625. I'm having a problem with the trigger return. It has the stock ribbed main spring and a 12 rebound spring.

When the hammer block device is in the gun the trigger will not fully return I have had the gun apart a million times and connot for the life of me figure it out. I was changing parts from another N frame and the only way I could get it to work was using the hammer from the other gun and it worked flawlessly. So I am guessing that I should replace the hammer in this gun.

Any ideas to where the hammer block is binding with the hammer?

Thanks

 

[a468bu]

It's only when the hammer block is in place. Works normal and fast reset without it.

 

[haggis]

Put in a 14-15 pound rebound slide spring and see if that fixes it. 12 pounds is just too light for reliable operation (that's 2/3 the weight of a factory spring). I can't imagine that you can get anything resembling a "fast return" with a spring that light.

One other thing, don't remove the hammer block safety - it's an integral part of the drop safety. There's a cadre of "gunsmiths" (bubbas) out there that say you can - don't believe them for a minute. Pate's book has an entire appendix on the development of this hammer block design during WWII - the results are very enlightening if you want to see data rather than jack-leg BS.

Buck

 

[a468bu]

I sanded filed and smoothed the hammer block. I smoothed the bottom of the hammer and all sides of the rebound box. No matter what the trigger will not return with the block in there unless I use the hammer from a different gun. It is a very very good and fast reset with the 12lb spring. I've tried different strain screws setting etc.

 

[ImprovedModel56Fan]

I've tried different strain screws setting etc.

There are no strain screw settings. There's only fully screwed in and partially disassembled.

 

[scooter123]

Haggis has it correct, put a 14 lbs. Rebound Spring in the lockwork. Doing this will only increase the Single Action break by about 1/2 lbs. and it won't have any measurable effect on the Double Action trigger pull. By going to the heavier rebound spring you'll save yourself a lot of work and it will have almost no effect you can actually feel on the trigger.

The only other option will require a good deal of work. Since you mention that a different hammer solves this problem it's a clue that the groove in the sideplate may be just a bit shallow or that your hammer may be rubbing on the sideplate. One way to identify the problem is to get some Dykem Machinists Blue and paint the inside surface of the sideplate to identify what is rubbing. BTW, also pick up a can of the cleaning solvent at the same time because that dye is somewhat impervious to mineral spirits and you'll need to have your sideplate totally clean for final assembly.

Your solution is to use the hammer that you have and stone it's width inside the lockwork cavity narrower by perhaps 0.001 or 0.002 inch. You could also try stoning the top surface of the hammer block where it's probably being pushed into contact with the sideplate by the same amount. Because both parts are hardened steel you will find out why the Surface Grinder was invented way back when, because flat stoning these surfaces will probably require a few weeks of rubbing the parts over an oiled stone. BTW, don't even think about using a Dremel, you won't get the parts flat stoned properly and probably just butcher them.

 

[a468bu]

I have tried absolutely everything at this point. I think there is no other choice other than to replace the hammer at this point since the gun works 100% with the other hammer in it. So where can I buy a whole new hammer assembly. The black dear drop style. Will smith sell me one?

 

[chief38]

Your hammer block safety might be bent or have excess metal on it. Is the hammer a MIM part? Is it oversize? Check for wear marks and rubs - tell tale hints.

 

[a468bu]

Ok I finally got it! It took me 3 days and some loss of sleep but I finally found the issue. As a last ditch resort I decided to really go after and stone the top of the hammer block and taper it. Where it slides up between the frame and the hammer. All is good now. I can't tell you how much this has been driving me crazy. Thanks to everyone that replied.

 

[Alk8944]

Ok I finally got it! It took me 3 days and some loss of sleep but I finally found the issue. As a last ditch resort I decided to really go after and stone the top of the hammer block and taper it. Where it slides up between the frame and the hammer. All is good now. I can't tell you how much this has been driving me crazy. Thanks to everyone that replied.

Just a few weeks ago I had a N-Frame gun, don't recall the specific model, that had exactly the same problem. There are at least two things that can cause this situation.

1) The rebound position of the hammer should leave .090" clearance between the hammer face and the frame. If less then the hammer block will drag. This sounds likely to be the issue with your gun, if thinning the hammer block "flag" got it working. The correct way to fix this one is to fit a new rebound slide so the hammer rebound is correct.

2) The one I worked on had a burr on the right side of the hammer face that was actually cutting a groove in the hammer block's "flag" and keeping the block from coming between the frame and hammer. When this burr was stoned off the gun worked perfectly. It originally acted like a cut rebound slide spring, but it was a full 17 turns!

I will say that logically it seems that the above mentioned burr on the hammer face should have been beat down by contact with the frame if the gun had ever been dry-fired, but it wasn't! In retrospect maybe that would have fixed the problem, simply dry-firing a few times!!!! Please note that this is not an endorsement or recommendation of dry-firing any gun, I have seen it cause far more issues than it ever cures. I only mention this as I find it hard to believe that here was a 35+ year old revolver that had apparently never been dry-fired, but that has to be the case!