Just fired my totally rebuilt S&W Model 10 .38 Special Ctg. made in about 1914. It had been burned in a fire and I rebuilt it from scratch..every tiny piece cleaned and oiled. I replaced the main/hammer spring with a new one off ebay as the old one was missing for some reason.
When I fired it for the first two times, I did so from a locked vice on a remote bench. It fired fine that way. BUT when I hand fired it using the trigger, it would not ignite the rounds. It only dimpled the caps. I could thumb the trigger back and it would fire fine. Did I get a weak main/hammer spring? Any ideas ?

The only thing which would cause a light primer strike would be a weak spring, assuming there is nothing impeding the hammer movement. Did you adjust the spring tensioning screw properly?

The spring may be weak, but a more likely candidate would an altered (or loose) strain screw. A previous owner may have shortened it to give it a lighter pull, and gone a bit too far.

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Why, I aughta.....

Adjust the strain screw….ok…I know what /where that is…I had it out when I cleaned the gun….do you screw in as much as possible or what..how is it adjusted ??

I have always heard - all the way in.

Would love to see pics of the completed gun.

Yes. Screw it all the way in - we assume it has not been shortened, but that is a possibility.

Incidentally, it cannot be a Model 10 if it was made in 1914. The Model 10 did not ship from the factory until 1958 and the M&P line went through lots of engineering changes between 1914 and 1957, some major and some minor.

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Jack
SWCA #2475, SWHF #318

The mainspring strain screw is not an adjustment device. It provides set in the mainspring that can be relaxed for purposes of disassembly. Its proper position is all the way down, fully tightened. If you still get light strikes with the strain screw fully in, try replacing the screw with a new one.

Larry

Okayyyyyy . I read that the gun was detail stripped and cleaned , and a mainspring ( of unknow provence) was installed. Was the * Rebuilding * process not mentioned in the post ?

Am I the only one to notice that the gun was damaged in a FIRE ? I have always been told that if a firearm is exposed to a serious fire to the point that the wood is damaged from flames or heat , you should consder it unsafe to fire until someone competent to do so declares it unaffected.

But in general , light strikes are a sign that the firing pin Strikes with insufficent force. We generally assume that is a sign of inadaquate spring energy , but it could be a full power spring , but excess drag / friction is taking place slowing the hammer fall.

In 1914, steel heat treating was not yet performed by S&W, and mild steel was the material of choice. I doubt that being in a fire would affect the tensile strength of the metal very much, and I wouldn't expect any problems if ammunition used was limited to low pressure standard loads. Of course, it could easily affect springs.

Once upon a time, I bought a 3" M36-1 that had been through a fire. I cleaned it up and had it Rockwell tested.

It shot fine.

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John 3:16
WAR EAGLE!

Completed gun...

That gun was made after 1921, not 1914. And, it appears to have a large ejector rod knob. So, it was likely made in the 1930's. What's the SN so we can date it?

In order to change characteristics of steel, the temperature would have to be much higher than a typical wood fire can generate. I have a .32 RP that belonged to my grandfather. It burned in a house fire in the 1950s and still shoots fine.

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Guy
SWHF #474 SWCA LM#2629

I would relubricate everything then replace the strin screw.

I suspect there's a 'V' in the serial number that is being ignored.

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Chris
SWCA #2243 SWHF #292

The ENTIRE serial number…is….595475 and in light print is says: "ODIN ALEX VA" What I can find out is that it was made in about 1929..sent overseas and then sent back to the USA…

I checked and managed to turn the spring tensioning screw about ⅓ of a turn further in to bottom it out and guess what? It fires correctly…I went ahead and ordered new hammer spring and tensioning screw from Numerch arms anyway…less than $20.