Hammer Drag - Right Side

[TheTinMan]

UPDATE - see 12/9 post

My "new" 1976 vintage Model 25-2 looks great on the outside. Unfortunately, on the inside it looks like it was made by the same guys that made the Vega & the Pinto (sorry fans!). I was really surprised because my 1990s vintage 66-4 and 642 actually are much cleaner looking inside.

After shooting about 150 rounds and a lot of dry firing, there's clear evidence of the hammer dragging on the frame on the right side.

Two main things I noticed: While there's a nice, round mark on the hammer's left side for the frame boss (2nd pic), there isn't any indication of contact between the right side of the hammer and the sideplate boss. The second thing is that the sideplate boss is far from level on the same plane as the inside of the sideplate. I checked it visually and measured to be sure. The top edge is significantly higher (toward center) than the bottom edge. However, you don't see any indication of the higher edge dragging on the hammer in the first pic.

I think that I need to level out the sideplate boss and get 1 or more shims. Is that the right approach? Are THESE the right shims? I was amazed that Brownells didn't seem to stock them.

BTW the bare metal you see on the upper edge of the sideplate and on the frame was started by the hammer. Both edges were proud of the inside surfaces, so I stoned them level.

Also, the vertical stripe almost directly above the hammer pin inside the frame was started by the hammer. I had stoned smoother it when these pictures were taken.

Another unrelated question: What's the best way to clean up the inside of the hand slot? It is REALLY rough. Is there a particular stone shape I should get? I can feel the hand dragging in there and see the problem areas on the hand.

Finally, here's another pic showing the inside of the frame and the bottom of the rebound slide. Yes, I've already polished the bottom of the rebound slide and that's what it looks like.

I also discovered that the pin going through the rebound slide was proud of the back side.

One last note to reassure you all - I have NOT touched the hammer with a stone.

 

[haggis]

I think you've got a good handle on what to do. You might want to reassemble the gun and see if there's enough "wiggle" to put a hammer boss shim on the right side. My concern is the raised circumferential rim on the left side hammer boss that is leaving a mark on the left side of the hammer. It's hard to see in 2-D, but that appears to be fairly proud of the boss surface and could prevent you putting a shim on the right boss. That might necessitate removing that raised rim so that you could install the shim without the whole thing binding up. You might want to remove it anyway - I doubt it's doing anything good for trigger pull smoothness.

I don't know if there's a stone made for the hand slot. I think there may be a special purpose file available. I have made my own from a thin, flat Swiss-pattern file that's about "half-a-hand-slot" thick, and removing the teeth from one edge and one side with a belt sander - go slow and keep the file from getting too hot. Just smooth the high spots in the slot - you don't want to widen it any.

Buck

 

[cjw3]

I'm thinking that if you stone the flat sides of the hammer (where it won't show), you may be able to get what you are looking for without a shim. Just a guess, but I have had the same sort of wear on some of mine and stoning the high boss(es), frame and hammer flats solved the problem.

As for the hand slot, I have used a sliver of ultra fine 600 grit sandpaper about 2" long by 1/8" wide. I insert it in the slot and sort of buff it back and forth a few passes, nowhere nearly enough to enlarge the slot. I picked up set of 4 Arkansas ultra fine stones that are 3x1/4" square, 3x1/4" triangle, 3x1/4" round and 3x3/4"x 1/8" back knife blade. I talked to a guy that runs a knife shop about it and he said it is fairly easy to score these types and break off whatever section you need to fit in a tight place. I've had a couple of times where I wanted to try it with that knife edge stone but I haven't gotten around to it yet. That is an awkward place to see what you are doing; I have to use a bright light and a magnifying visor/loupe.

P.S., I think you can get a lot more aggressive on that rebound slide, bottom and sides. I can't quite tell how much you have worked on the bottom mating surface in the frame but I am always pleasantly surprised at how just a little effort there and on the slide itself smooths up an action.

John

 

[Hearsedriver]

A belt sander (stationary) with an 80 grit belt will shape Arkansas stones to whatever thickness you need and it does it fast.

 

[tomcatt51]

Are THESE the right shims? I was amazed that Brownells didn't seem to stock them.

That's them. Bownell's carries them also:
S&W SIDEPLATE SHIMS - Brownells

 

[TheTinMan]

Thanks tomcatt! Brownells' search engine still doesn't always turn up what I'm looking for, even though it's so much better than it used to be. $1 more at Brownells but well worth saving a second shipping charge.

 

[minconrevo]

It can be a project to get certain builds of S&W revo's running well. The hammer and trigger pins have to be dead square to the frame. The excess metal left by less-than-perfect milling of the various frame surfaces must be carefully filed, then stoned clear/flat. Sometimes the bosses may not be square. Sometimes there are burrs in the dangest places inside the frame. Next comes the careful fitting of just enough (but not too many) Powers hammer and trigger sideplate washers. The washers have to go on the correct side(s) to center things up. Sometimes the hand is poorly fitted. Never say never can happen inside a revolver.

The reward is when everything is just right, the action is buttery smooth and totally dependable.

 

[TheTinMan]

Well, I'm about to place an order with Brownells including shims for both the hammer & trigger. I hadn't noticed a wear mark on the left side of the trigger... Don't worry Buck - there's plenty of wobble in both!

 

[1 old 0311]

That is the roughest S&W frames I have seen. Good luck.

 

[Hearsedriver]

Someone used a very dull endmill to mill that frame! It can be smoothed but it will be a lot of work.

 

[TheTinMan]

Honestly, I'm really glad to know that this rough metal work is unusual. Otherwise I'd have to go back to buying only old Colts (gasp!)

My two mid-1990s Smith & Wessons, a 642 and a 66-4, both have much better workmanship. I think this Model 25-2 must've been made either on Monday morning or late Friday afternoon...

 

[Nightowl]

Brownell's also has hand window files. Be sure to only file the frame side of the slot, not the sideplate side.

 

[TheTinMan]

UPDATE

The hammer & trigger shims came from Brownells today, so I got to work. First, I did my best to level the hammer boss on the sideplate using stones - it was way off compared to the inside surface of the sideplate. Then I put one hammer shim on the frame side (left) where that nasty rim is plus 3 on the sideplate (right side). Actually, I added shims until it started binding and then removed one to get to 3.

After that, I looked at the wear marks on the left side of the trigger. If you look at the last photo in the first post, you can see the really nasty machining marks on the inside of the frame just below and behind the trigger pin. Big surprise - that's where the trigger was starting to show drag marks. I carefully stoned that area level with the inside of the frame. Not trying to make it look right, just smoother than before. Adding one trigger shim on the frame (left) side took most of the wobble out and I think (hope?) it will stop the drag marks on the trigger.

Oh, I also spent a lot of time on the rebound slide trying to polish it up. About 50% of the bottom surface is polished now compared to 30% or less in that earlier photo. I should've taken a pic before even trying - it looked like a new cast iron skillet!

Earlier, I had experimented with Wolff replacement mainsprings. Their "standard" power mainspring actually increased double action trigger pull a bit. The reduced power spring dropped DA pull from 11 lbs. 5 oz down to about 10 lbs. 3 oz. Single-action trigger pull is right at 3 lbs even so.

All of the work described above didn't reduce the trigger pull much but it sure as heck smoothed it out a lot!

As my final act of blasphemy, I replaced the beautiful rosewood grips with a Hogue monogrip. I intend to shoot this gun and the factory grips were too big and shaped a bit "off" for me. I really like the Hogues for shooting purposes despite the fact that they make the gun look cheap.

Thanks for helping me out.