Double action top break

MHF · #1 01-19-2021, 06:11 PM

I have recently acquired a S&W top break double action of the 4 model. The old gun is in fine shape and with the box. My issue here is when the pistol is cocked and a little pressure is put on the hammer it falls. I don’t think it has been fired very much, but I would like to fix this failing.

Wiregrassguy · #2 01-19-2021, 06:39 PM

That is a beautiful .32 Double Action! The condition you describe is called "push off." You might want to tighten your strain screw on the inside bottom of the grip frame as it look to be unscrewed a bit. It should be fully seated. If that doesn't fix it, it may be dirty inside the action. So, I would take off the grips...carefully...don't pry because it may break off the bottom where the grip pin engages the panels. Then, spray the insides with aerosol carb/parts/brake cleaner until the effluent runs clear. If that doesn't fix it, you may have to open the sideplate and inspect the single action sear to see if it may be chipped or worn. A good gunsmith can probably fix it with a few swipes of an Arkansas stone.

MHF · #3 01-19-2021, 07:38 PM

Thanks, I also noticed the hammer would not engage in the "safe" mode. I just dont see how it could be damaged badly with the amount use, or lack of use.

Wiregrassguy · #4 01-19-2021, 08:22 PM

If by "safe" mode you mean half-cock, there is no half cock on a double action. I agree that it looks too good to be excessively worn, but you never know. Someone might have tried to do a trigger job on it. Anyway, chances are a good cleaning will do the trick.

mmaher94087 · #5 01-19-2021, 09:15 PM

Try the cleaning first after tightening the strain screw. Please don't pull the side plate as that leaves an ugly, visible line and reduces the value in my opinion. When spraying the crud from the action; cycle the action to help with the cleaning. When clean, spray lubricant inside. Rem Oil is good.

glowe · #6 01-20-2021, 09:50 AM

Sorry to disagree, but one will have to remove the sideplate in order to see what is wrong with the trigger or sear interaction. This model had a real problem with hammer push-off, partly since the parts are so small. Often found with a chip missing either on the trigger or sear is the cause. I would guess that the gun is quite clean inside, looking at the exterior.

If you can find a gunsmith that will work on a top-break revolver, and the gun has not already been fiddled with, it can be repaired. I have purchased two of these guns that were pristine, except neither held in single action. Repairs were made and guns both functioned like new.

Please do not try to shoot the gun until repaired. A friend owned one of these many years ago and decided to shoot it and said he would only use it in double-action mode . . . well he forgot one day and shot the shooting bench by inadvertently pulling the hammer back to shoot in single action mode.

mmaher94087 · #7 01-20-2021, 11:41 AM

"Try the cleaning first.." If that doesn't fix the problem then I agree with Gary. Finding a gunsmith that is willing to work on a top break could be problematic. Parts are getting more difficult to find also.

glowe · #8 01-20-2021, 12:01 PM

Some are fortunate to have a gunsmith willing to tackle something new to them. I picked up this 6" 32 DA cheap and it had a chipped hammer ledge. My guy was able to micro-weld the hammer ledge and reshape to function perfectly. As Mike says, parts are hard to find, so this is an option for repair.

MHF · #9 01-20-2021, 01:34 PM

The sear fit looks awful

MHF · #10 01-20-2021, 01:35 PM

It’s clean inside

mmaher94087 · #11 01-20-2021, 02:09 PM

Am I seeing junk stuck in the hammer notch? Run a dental pick across the hammer sear and see if crud falls out. NO files, please.

glowe · #12 01-20-2021, 02:51 PM

It is easy to remove the hammer and get in there with a magnifying glass to see if the sear is damaged. Remove the spring tension by backing out the butt frame strain screw and pushing out the bottom of the mainspring. You should then be able to wiggle the hammer until it comes off the stud and out. Use the magnifying glass to check out the lower ledge for any imperfections as well.

MHF · #13 01-20-2021, 09:06 PM

Yes, is was a small amount of crud in the hammer sear. I took a tooth pick and ran it back and forth and it discolored the tooth pick. No big chunks.
It didn’t help!
I have a 38 dbl action I’m going to take the side plate off tomorrow to practice fiddling with the hammer. The nickel plate is pretty fragile on the 32 so I’m Leary about pulling the side plate off to many times.

mmaher94087 · #14 01-20-2021, 10:45 PM

Over the net diagnostics is iffy at best. My opinion is that the single action sear is chipped (broken). The sear end that contacts the hammer should be rounded like a fish hook and the sear would be where the barb would be and at a slight back angle. Your sear appears straight up and down and not slightly hooked. Your .38 sear should show you the slight hook. Please keep us posted.

MHF · #15 01-21-2021, 12:12 PM

The hammer sear is in rough shape.

MHF · #16 01-21-2021, 12:46 PM

It appears that the trigger sear (or front sear) is just as rough, although I can’t photo it, but what next? I need a hammer and sear for 32 dbl action?

What have I to loose by polishing the rough spots of both sears?
And I understand the hardened surface is microscopic!

BMur · #17 01-21-2021, 02:38 PM

Before you go messin' with the sear and hammer?

Check the sear spring tension. I'll post a photo later. I've seen so many sears ruined when the sear was "never" the problem. It was a weak spring.

The sear spring is a very common failure on these. It is under tremendous stress when the gun is cocked and often it will either loose its tension strength over time or develop a hairline crack. This common problem Often fools the operator thinking that the sear or hammer need tooling when they don't.

Murph

mmaher94087 · #18 01-21-2021, 02:40 PM

Slight clarification: The front sear is the double action sear. The rear sear is the single action sear. "What have I to loose by polishing the rough spots of both sears?" Not much but too much polishing will affect the cylinder timing and lock up. Ideally, the cylinder locks just before the hammer reaches full cock. Check with Gun Parts Corporation, Jack First etc. for the parts as you may get lucky.

BMur · #19 01-21-2021, 04:19 PM

Here are a couple photos.

First photo is an Excellent example of what I’m trying to convey regarding hammer slip. The 3 Smith & Wesson sear springs show different levels of wear. The worst is the one on the Bottom. The middle spring I re-arched to The correct angle. That’s my spare for now. The top spring was functional but occasionally slipped off lock up. The correct repair is to carefully heat the spring and re-apply the correct arch.

2nd and 3rd photos show how important the correct arch is on the sear spring to maintain lockup. Without designed spring tension the hammer will slip off.

So, the absolute first thing to do is to confirm spring condition “ BEFORE” you stone the slots!

So many sears and hammers have been filed on! When the entire time it was the spring that was the culprit!

Murph

BMur · #20 01-21-2021, 05:58 PM

Here is a photo showing a good hammer on the right and a destroyed hammer on the left. Someone took a file to it so intensely that they even dug into the saddle link/ stur-rup.

It can be repaired with a weld but it’s a pain because it is done in stages to fit and function, so it’s time consuming.

Murph

MHF · #21 01-21-2021, 07:15 PM

Thanks, that is a lot of help. I've been looking online all afternoon and I think I found all 3 parts, and I've got them on the way.