Lightening a Leaf Spring

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wasrupzuk

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So I have a hammer leaf spring which is way to heavy (off the scales and punches the odd hole in primers) it’s an old gun and I believe a gunsmith made the spring as originals are not an option.
It’s very well made in my opinion but the trigger pull and hammer drop is way to high.
So what is my best option to lighten it?
Thin it, narrow it or a combination of both?
I know that thinning has to be uniform front to back and smooth (no stress risers) plus don’t get it hot.
Thinning seems the right answer to me but narrowing is far easier/quicker (my main thought as to why that’s the wrong answer...).
Or an I over thinking this?

Any help is appreciated,
Thanks
 
I do believe the sequence is to soften it, then thin it, then temper it, then draw the temper. Don't think you are going to grind down a tempered spring, and still have a tempered spring. Older books - Modern Gunsmithing - Clyde Baker - 1933, The Modern Gunsmith - Virgil Howe - 1934 describe the process.
 
Punched primers may be caused by firing pun nose shape.
Have a look at it.
I have both thinned and narrowed a vee spring.
To thin I use a sanding drum turning lengthwise, never across!
I assume this is a vee spring, so not available on the "compression" side.
 
You can file if the spring is soft enough, or you can grind with a Dremel provided you are very careful to never let the spring get hot. If you see color change your already too hot. Grind a few seconds then dip in water. You should ideally hold the part in your fingers so that as soon as you feel a tiny bit of heat you know to dunk it. Thinner and narrower both work, depends on how light you're trying to make the spring.
 
I will go along with Tiriaq that you can probably file the spring. Myself, I would probably grind it a bit more narrow (side to side) and definitely not thin it vertically. I would finish by drawfiling. I definitely would not try to anneal and reshape and retemper it. I make and temper 6 to 10 mainsprings per year and while I do not consider it a difficult job, I also work only with one type of steel and draw the temper in molten lead using a high temperature thermometer. It is not something I would recommend an inexperienced person to do with an original spring or with a spring made of an unknown type of steel
I also would confirm first that it is not the shape of the tip of the firing pin which is the problem. It could also be something as simple as a return spring on the firing pin being missing and allowing the pin to travel too far forward. The hammers on many original guns are pretty strong in my experience

cheers mooncoon
 
oldstarfire said:
Punched primers may be caused by firing pun nose shape.
Have a look at it.
I have both thinned and narrowed a vee spring.
To thin I use a sanding drum turning lengthwise, never across!
I assume this is a vee spring, so not available on the "compression" side.
Click to expand...

Firing pin is the same as my other gun and appears normal.
The 25 pound trigger pull isn’t...
Yes, it’s a V spring.

Grizzlypeg said:
Can it be reshaped to lessen the preload?
Click to expand...
I don’t believe so.

Sniper_485 said:
You can file if the spring is soft enough, or you can grind with a Dremel provided you are very careful to never let the spring get hot. If you see color change your already too hot. Grind a few seconds then dip in water. You should ideally hold the part in your fingers so that as soon as you feel a tiny bit of heat you know to dunk it. Thinner and narrower both work, depends on how light you're trying to make the spring.
Click to expand...

I was thinking the Dremel tool would do it.
Basically I have to half the strength. Compared to my originally sprung gun the spring is considerably fatter so I think it’s doable.

Thanks for the help guys.
 
If you try to grind the spring consider a power wet stone. I made a new spring for a cylinder hand in a Uberti 1875 six shooter from a clamp style paper clip. This is a very small spring and I was able to do it without taking out the temper.
 
Diamond files work fine. Thinning a spring will have a muchgreater effect with less material removal. Given equal weight, a narrow, thick spring will be quicker than a wide thin spring.
 
wasrupzuk said:
Firing pin is the same as my other gun and appears normal.
Click to expand...

You have 2 of the same gun?? swap the springs around to eliminate the possibility that it is the firing pin. (then swap the pins to confirm that it is the spring)

Someone mentioned wet grinder. Do that. Thin or narrow it, both will work narrowing it will give you a bit more forgiveness from grinding too far and less chance of breakage.

You could also make an entire new spring in probably 1/2 hour.....
 
Storing it cocked will slowly reduce tension... flexing is what eventually makes it necessary to have replacement leaf springs made.

If you want immediate results, other chaps have suggested sanding or filing... I second the guy who mentioned completing this action along the length of the spring not perpendicular: any small blunders, or marks perpendicular to the length of the spring become weak spots where premature breaks will likely occur... unless your finish surface is flawless.
 
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