Mainspring question

[Long John]

Friends,

A friend of mine brought me his English Fusil made by ******* with the complaint that the gun would nolonger spark except with an exceedingly sharp flint, but even then, after a couple of shots it would nolonger spark.  This gun used to be a reliable sparker, even with worn flints!  I first thought that the frizzen was worn through but a file skates across the frizzen face without a single mark.  The mainspring tension on the hammer seems whimpy compared to the Siler (Chambers) locks that I use on my guns.

Before I make a fool of myself and ask the manufacturer for a replacement spring I am trying to eliminate all of the other possibilities.  I sooted the lock, installed it and worked it a bunch and then removed the lock to look for binding/rubbing issues but found none.  I plan to dissassemble the lock and tune it up to see if that helps.  However, I need to know: Is it possible for a spring to loose its force over time?  Is it possible to reheat, quench and then retemper the spring to restore its former force?

Thanks for any insight you can bring to my questions.

Best Regards,

John Cholin

[D. Taylor Sapergia]

John, if the spring was tempered a little soft, it may have taken a set that has somewhat reduced its power.  If the spring has enough steel to make it effective, and it sounds like it once was, you can heat it red, increase the throw ( the foot should be about 1/4" below the tumbler's toe with the spring out of the lock but in position) then heharden and retemper it.
On the Davis Twigg lock, for example,  the mainspring is a real buggy whip...very long and thin.  Only with the lock perfectly tuned will it give good spark.

[Sam Everly]

John you said a file will not mark it ! Well you just answerd your own question , the frizzen is to hard . Light or heavy spring it should still spark . Try to draw back the frizzen first. Try 375 dges for one hour if it will not mark with the file the try 400 for one hour.

[D. Taylor Sapergia]

That's good advice Sam.

[rich pierce]

You could also try a "booster spring" to see if that helps before going to the trouble and risk of bending, re-hardening and re-tempering the mainspring.  Make or add a thin spring that fits inside the mainspring bend and that bends wider than the existing spring at rest.  Lots of backwoods guns had this sort of fix or even a piece of wood forced into the bend.  Those were meant to be emergency repairs to keep the gun firing until a gunsmith could properly replace a wimpy spring, but many times they became, as my Dad would say, "Just permanent".  Anything from an extra old sear spring to a frizzen spring could be adapted for this.  There is risk as you'll be making the rest of the speing work a little harder also.

[Roger Fisher]

An easy check and only a thought; but have you had a close look at that main spring??  Could it be that it is carcked partly thru and ready to 'go' completely??

Of course things are seldom that easy!!

BTW we had 33 shooters yesterday at our somewhat rain storm shortened shoot!
 

[Stophel]

John you said a file will not mark it ! Well you just answerd your own question , the frizzen is to hard . Light or heavy spring it should still spark . Try to draw back the frizzen first. Try 375 dges for one hour if it will not mark with the file the try 400 for one hour.

I make all my frizzens so that the face is rock hard and a file won't touch it.  They spark like a house on fire.  I am able to temper the front of the frizzen upright a bit so that it is fileable (though just barely), and therefore a bit springier.

[Dphariss]

I would probably re-arc the spring so it has a little more curve and reharden/temper.
Chances are the one you get as a replacement will be little better.

Dan