Too strong a spring - how do you fix this

[Sudsy]

Ground it on the belt sander, polished the edge - 16 lbs
Redid it - 10.5 lbs
Do it again ? Is 10 (ish) the right number?

Also, it's polished to 800 grit, is that enough ? I can take it all the way to 2000 but that seems overkill

 

[The Appalachian]

Sudsy, really, as long as you've cleaned up any deep scratches from the belt sander you're good to go. Look at it close in strong light or use a magnifyer. I personally polish with a dremel and polishing compound but I'm anal about some things. If it's polished really well then it's just insurance that scratches won't break it.

As far as the poundage, assemble the lock and try it. The base line is good sparks, not difficult to cock, and flips the frizzen all the way forward. Flint longevity is secondary for me to reliable function.

 

[M. De Land]

Ground it on the belt sander, polished the edge - 16 lbs
Redid it - 10.5 lbs
Do it again ? Is 10 (ish) the right number?

Also, it's polished to 800 grit, is that enough ? I can take it all the way to 2000 but that seems overkill

Yeah, that's plenty, actually 400 grit is enough as long as all file cuts or edge corner micro cracks are removed, usually found in or near the turn back when forged or heat treated. It must be remembered that emery grit fractures and rounds off grains as it works . 400 grit very quickly breaks down to a much finer grit as it abrades steel.
Another help to promote spring longevity is to radius all sharp edge corners inside and out. Sharp spring corner edges, in high stress areas are the first place cracks originate.

 

[GREENSWLDE]

Looking at Appalations photo with the black and red lines it's obvious that the bottom arm is going to bear on the upper arm a short distance from the bend which means only the leaf outside the contact point is the opperating spring while the bend is an open loop instead of being closd to about a .015"/.020". Without a total re-work you don't stand much of a chance. Heat it to cherry red and flatten the bend with a thin shim (say .020") thick in the bend at the same time as flattenig the bend of the bottom leaf. While it's still soft reduse the thickness of that leaf and shape to a smooth curve. Smooth the lot and then re-harden and temper thru' straw and violet to dark,deep blue. Polish the whole inside and out as the posts say and you sould be Good to Go. Silk purses can "Sometimes" be made out of Sows Ears. Old addage -- Nothing Ventured, Nothing Gained and you've learned along the way.. I learned,sitting next to Nelly in the late 40's..Regards to M.de Land.. OLD DOG..

 

[Sudsy]

Another help to promote spring longevity is to radius all sharp edge corners inside and out. Sharp spring corner edges, in high stress areas are the first place cracks originate.

Ah crap, didn't do that
Taking it apart again

 

[M. De Land]

Ah crap, didn't do that
Taking it apart again

I'm trying to figure out if your spring is cast or forged . The swell on the inside corner of the turn back happens when spring stock is heated and reversed "forged" . The capture loop at the top makes me think of a casting but could have been formed from a wide blank , cut out, drilled and 90 degree bent under heat. My best guess from what I can see is that it is made from spring stock and shaped /forged .

 

[deerstalkert]

Is the back of the spring scrubbing against the lock plate any where?

this and also check for binding anywhere in the inlet. did i already post this? Dija vu all over again!

 

[GREENSWLDE]

If your making your own from sceatch Make a narow "v" shaped punch wider than the springs you want to make and a "v" block the same angle. Makes it easier to start the bend. Helps to stop so much flair. The flair can always be flattened on the anvil while spring is still red.Start with thicker and wider blank and you can remove any flair left. Not trying to teach App. or M.de to suck eggs.Just to help NEWBEE'S with some thing to improve there Repro's.. O.D.

 

[Rifleman1776]

Reading all the posts here and his efforts to lighten that spring really bother me. Call me chicken, or whatever, but it long has been my policy to never mess with springs, especially ml mainspring. I seem to recall that I did once for a Jaeger with a Davis lock but bought a spare spring before attempting anything. It is too easy to mess up a mainspring. Ruin it and your don't have a gun anymore.

 

[Sudsy]

Reading all the posts here and his efforts to lighten that spring really bother me. Call me chicken, or whatever, but it long has been my policy to never mess with springs, especially ml mainspring. I seem to recall that I did once for a Jaeger with a Davis lock but bought a spare spring before attempting anything. It is too easy to mess up a mainspring. Ruin it and your don't have a gun anymore.

This thing was so over strong it was shattering flints, I was lucky to get 10 good shots
So nothing here to lose