? on Combat Masterpiece - main spring and firing issue

[bedbugbilly]

I have a nice Combat Masterpiecd - I believe DOB of 1955 (from what I was told on here). Serial No. is K 2486XX. This revolver has very little blueing wear - just slight lightning of blueing at muzzle edge from probably holster wear. It does not appear to have been fired a lot. I have only had a chance to shoot it a few times.

So my problem . . .

I only shoot my lead cast reloads. I've always used CCI primers with no problems in any of my other vintage Smith 38s, Colts, and my multiple SA 38/357s.

The last time I shot my CM, I had no problems with every round going bang in SA. But, shooting DA, I had probably 4 or so out of 20 that didn't go off. The second time around in the cylinder they did. At first, I though I may have a primer seating problem (I hand prime with a Lee ergo primer) but on inspection, all looked correctly seated.

Some complain of the hardness of the CCI primers - again, I've never had an issue. I switched to Winchester primers but haven't had a chance to try them yet. The two LGS I go to both only carry CCI or Winchester primers.

I checked the mainspring tension screw . . it was seated all the way in tightly. I removed it and there are no signs of being "bubba'd" to lighten things up. The hammer mounted firing pin looks fine and it makes a good dimple on the primers when fired in SA and usually in DA . . but on the cartridges that didn't go off, it looked like a light hammer strike. Checking the CM unloaded, nothing showed up as far as anything hanging the hammer fall up or slowing it down - no wear on sides of hammer or hammer groove in the frame, etc.

My question is . . on a CM that is roughly 60 years old and one that has probably not seen a tremendous number of rounds . . . is it possible that the main spring has weakened? I know nothing o the history of my CM but there are no PD or military markings and my guess would be a sock drawer gun that maybe got shot once in a while.

I realize the hammer is going to hit harder in SA than DA. It just seems that from what I'm seeing when cycling in DA, it is falling on the light side.

Should I be thinking of replacing the main spring? If so . . with what? Does the CM take a standard K frame main spring? I don't care if the trigger pull ends up a little heavier as I always "learn" the individual pistol I'm shooting and adjust to what the trigger pull is.

Or is it just that this particular CM is going to be "finicky" with CCI primers when shot in DA?

Or is there another problem that might be hampering the hammer fall in DA to make it too light? I haven't pulled the side plate but it appears to be very clean with the grips off, looking up in, etc. and the action seems very smooth and easy.

Comments, suggestions or things to look at?

Sources of a good replacement main spring if that should be necessary?

Thanks.

 

[Peak53]

You are right in that the symptoms appear to be linked to the mainspring, or at least to a reduced hammer impact. You said you checked the strain screw and it appeared OK, but wondering if you should check the length against one from a K frame you know has not been shortened. Aside from that, is it possible someone put a bend in the mainspring? It should be basically flat. Also check the trigger rebound spring for clippage. Should have 17 coils. If you decide to replace any of these inexpensive parts, I would get factory parts from Numrich for best, most reliable results.

 

[Alk8944]

Strain screws are fit at the factory by filing the end of the screw. Just how do you suppose you could tell it had been "Bubba'd" by looking at it? Being 60 years old there is a good chance someone has tinkered with the spring or strain screw.

Take the stocks off the gun, take a photo with the hammer at rest, and we can give you a good educated guess if it has been messed with based on the arch to the spring. The only way to judge is with a spring scale such as a trigger pull gauge. Form a wire loop around the hammer spur, or through the hammer nose rivet. Hook up the spring scale and pull back on the hammer to cock it. Watch for the moment the hammer begins to lift, the scale should read not much less than 7 1/2 pounds. With much less than this you are going to have ignition issues in double-action.

Forget hard, soft, or whatever primers. If your gun will not fire any primer in double action you don't have enough spring tension, resulting in too little hammer energy.

"....the action seems very smooth and easy." This is the first indication that there is inadequate spring tension!

 

[DWalt]

Springs are the same as used in every K-frame. You might want to get a new spring tension screw (in case yours has been shortened too much) and flat hammer spring, won't cost much. While you are at it, you might as well remove and clean all components with mineral spirits, then reassemble and lubricate. You shouldn't need a new rebound spring, as that has nothing to do with the force exerted on the hammer.

If you want to check the length of your hammer spring, it should be close to 3.44". The thickest part near the base should be close to 0.07" and the thinnest part near the tip should be close to 0.03"

I firmly believe it's a myth that there are differences in primer "Hardness" from different manufacturers. All primer manufacturers control minimum primer ignition impact energy to the same specifications for the same primer types. This is not a guess but fact. I've been there.

 

[Blackshirt]

Springs are very affordable. I recommend that you replace your mainspring and rebound spring. If the springs in your K-Frame are original, they are past due for being switched out. Wolff makes decent replacements...check it out:
https://www.gunsprings.com/index.php?page=items&cID=3&mID=58&dID=264

 

[H Richard]

Being 60 years old and not been fired much, there is a possibility of a build up of crud from old oil and firing residue, In the right locations, that can slow down the action enough for an occasional light hit. Try a disassembly and thorough cleaning then lubed sparingly with light CLP. One possible way to tell if it is the strain screw is to take a fired primer cup (no anvil) and loosen up the strain screw enough that you can place the primer cup over the end against the spring. Tighten everything back down and try it then. If it fires o.k. it would point to a short strain screw.

 

[bedbugbilly]

Thank you to all for your responses. I am posting some photos of my CM showing it cocked and uncocked as well as a closer photo of the base of the main spring and the tension screw.

In response to the one post in regards to how I could determine if it was "bubba'd" or not. I am not an expert on S & W revolvers nor a pistol smith. I've only been shooting BP for 50 + years and cartridge guns (at least CF) I've only been shooting for the past 10 years or so . . . that's why I posted on this site. From my observations of the tension screw . . it does not appear to have been ground in a "bubba fashion".

I pulled my M & P out and compared the two different K frames. From what I am seeing on the CM, it may indeed have been altered. I will post the photos of the M & P in another response to this thread. The M & P tension screw is longer and the base of the main spring is pushed back tight against the groove the base fits in - not so on the CM.

Looking at this, my assumption is that I should probably order a new tension screw and a main spring and just change them out? Is this a correct assumption?

Are there any other parts I should order and change at the same time?

I will pull the side plate and do a thorough cleaning as well.

Thoughts, suggestions, comments greatly appreciated! Thanks for the help and advice!

 

[bedbugbilly]

These are the photos of my M & P that I compared with the CM. The tension screw IS longer and when screwed in all the way, the mainspring base is pushed back tight against the back side of the slot in the frame.

I have no issues with this revolver at all. All cartridges go bang when fired in SA and DA.

If I replace the mainspring and tension screw on the CM so that they are in this position, I'm assuming that will put more down pressure on the hammer when falling when fired in DA. Does that sound like the correct "fix"?

Thanks.

 

[Peak53]

I believe the tension screw has been filed short. Note that it appears flat in your photo and typically has a more rounded end against the mainspring. It's a $1.99 fix, although I would order a handful for your stock.

 

[MajorD]

A quick thing to try take a small pistol primer remove the anvil so it is just a small cap - place this between the tip of the Strain screw and mainspring and tighten down- if this causes the issue to go away you know the mainspring/ strain screw tension is to blame. You can if you like then replace spring and/ or screw. Honestly I used this fix and just kept the primer over the screw for years and thousands of rounds with no further issues

 

[AzShooter]

No no don't fix it! Sell it to me.

 

[nedlate]

These are the photos of my M & P that I compared with the CM. The tension screw IS longer and when screwed in all the way, the mainspring base is pushed back tight against the back side of the slot in the frame.

I have no issues with this revolver at all. All cartridges go bang when fired in SA and DA.

If I replace the mainspring and tension screw on the CM so that they are in this position, I'm assuming that will put more down pressure on the hammer when falling when fired in DA. Does that sound like the correct "fix"?

Thanks.

Quick fix-Swap the tension screw with your M&P and then try it out. You could also put a used primer under the end of your original tension screw. Replace the main spring if you want but I would try the tension screw first. I see I am a slow typist and MajorD already suggest the primer cup fix!
Ed

 

[bedbugbilly]

O.K. Thank you all very much! I'll try the spent primer with the anvil removed as well as swapping with the one in the M & P to see what happens.

For only being interested in CF cartridge pistols for about 10 years, I've accumulated far more than I ever expected. I have five vintage Smiths and a Colt or two. I love the K frames so when I order some tension screws, etc., I'll get extra. Somehow I have a feeling these won't be my only K frames!

Greatly appreciate the help and advice . . a continuing learning process!

Thank you again!

Jim