Flint lock tuning

[Pennsylvania Dutchman]

I have noticed that it has been mentioned in several threads over the couple of years that I have been here, that when a lock is well tuned the mainspring and the frizzen spring will be in balance. How does one determine if the springs are in balance? If it is determined that they are not in balance, what is done to balance them?
Thank you, Mark Poley

[Jerry]

Mark, That is a very good question. Many will benefit from this question. Jerry

[rich pierce]

A severe imbalance will result in problems. Both springs have to be “strong enough” to do their jobs. If the mainspring is  weak it won’t drive the frizzen open reliably or be anywhere near “fast”. If the frizzen spring is weak the pan could flop open and will certainly rebound, bashing the flint repeatedly.

If, in the quest for balance, either becomes too weak, you’re worse off than before. I just start with, “Is either spring too weak to do its job?”  If not and it’s sparking well, I leave it alone. It’s almost unlikely that a mainspring is too strong.

[smart dog]

Hi,
I typically want the force required to open the frizzen to be about 1/3 that necessary to bring the flintcock from rest back to full cock.  I measure the forces with a small spring scale. That is where I begin and then the lock geometry may indicate some adjustments as I test the lock.  I want the frizzen to offer resistance for spark but get out of the way as quickly as possible.  Some folks prefer a heavier frizzen spring, however, I tune a lock not just for the first shot when everything is clean and flint sharp. I think about the 10th and 20th shot when everything is dirty and greasy and the frizzen is grinding through fouling where it rubs against the frizzen spring.

dave

[Pennsylvania Dutchman]

Thank you all for the replies. The two locks that I have now are a large Siler on my smooth rifle and a small Siler on the pistol I built my son. I noticed that with a wood flint in both locks, when I trip the sear holding the locks in my hand, the small Siler will lay still in my hand as it fires, but the large Siler will jump slightly in my hand as it fires. Is that because there is more mass moving with the larger lock or is there a balance issue?
Dave, I will get a small spring scale and check both locks. Do you slightly thin the top leaf of the frizzen spring to lighten the pressure? Do you change the shape of the top leaf or the frizzen toe shape to change the timing of the frizzen opening on Siler locks?
Thank you all again for the help, Mark

[Darkhorse]

I would say your frizzen spring is a little stronger than neccesary. My interpretation of a lock that's imbalanced is when the trigger is pulled the entire lock jumps and moves your front sight off target. This is more easily seen on a rifle with set triggers. This is a condition I remedy as soon as I've determined it's the problem.
I clamp the frizzen spring in a vice and using a dremel tool I grind the top surface following the original contour as much as possible. Great care must be taken not to overheat the spring to where it changes colors. I make several marks with a majik marker along the length of the spring and measure at each mark with dial calipers and by checking each mark I can remove an equal amount from each spot. When the spring weight is where I want it I put a buffing roll with buffing compound in the tool and polish the surface I've ground thoroughly. I will remove all the grinding marks to get a smooth surface. The smoother the surface the less chance of a crack starting.
I want my frizzen to open at 3 pounds or a little less, checked with a trigger gauge hooked on the top of the frizzen. I never touch the mainspring as I want it strong and fast.
BTW the first thing I do is thoroughly polish the entire lock to include straightening the lockplate. Check that the frizzen screw is not too tight and that the side of the frizzen isn't rubbing the barrel. If after all this the problem persists I will consider thinning the frizzen spring.
Others may do things different but I get good results with this method.

[Pennsylvania Dutchman]

Thank you Darkhorse for your reply. I machined the lock plate from steel bar, so it is good and flat. I have the internals polished and the frizzen is unbridled and on a shouldered screw, so I think I'm good there. I will get a spring scale to see what it takes to open the frizzen.
Thanks again, Mark

[Daryl]

Further note, as to balance. If the frizzen spring is to soft, the blow of the cock could damage it over time due to battering.
That said, I have broken the feather/frizzen spring while on a trail walk and the rifle fired perfectly for the rest of the day,
with no spring holding the frizzen closed or against the cock's blow. There was no difference. This likely shows the geometry
of the lock was pretty good. It was an L&R Dickert Lock- a very fast lock indeed.

[Turtle]

 Years ago I went to a talk on locks by Jim Chambers. I remember him saying that a properly balanced lock shouldn't jump much when you spark it when held in your hand. at least I think that is what he said and I think it was jim chambers. I am sure it was at a Rendezvous and the sun was shining.

[jerrywh]

For the springs to be in balance is a good sounding theory. From personal experience it is my opinion that the main purpose of the frizzen spring is to keep the powder from dumping out when the gun is carried. Also it tends to keep the powder dry to some extent but not very efficiently.
   When it comes to tuning lock try this some time.  Take the frizzen spring off and fire the lock to check the sparks. You will see that it will spark much better with no frizzen spring. When I started out I made all my own locks because there weren't any to be bought. So I learned a lot by experimentation.  So how strong must a frizzen spring be?  It must be strong enough to stop rebound and keep the powder in the pan. It must be weak enough to allow total exposure of the powder when fired. That's about it. The main spring should be strong.

[Darkhorse]

Thank you for that Jerry. I think I might buy another frizzen spring or two and see just how light I can make it, and it still works properly. The smoother my rifles shoot the better I shoot. Looks like I might not have achieved my optimum spring strength yet. I'm willing work on this a little more for knowledge's sake.

[Marcruger]

I had a similar question regarding my incredible spraking Chambers late Ketland.  Initially it was hard on flints, with the edge getting destroyed in 3-4 shots.  I inquired and read up on this phenomenon.  I received good advice on balancing springs too. 

In the end, what was happening was that my strong frizzen spring was causing the frizzen to bounce back onto the flint upon firing.  The bottom of the frizzen was knapping the flint edge. 

After lots of deliberation, I used the very old-time solution of simply extending the jaw leather out to the end of the flint on the top side.  The leather pads the flint and prevents knapping.  Voila!  Works like a charm, and I am embarrassed to say how many shots a flint gets now.  Flattened lead apparently works just fine in this role too. 

Hope this is useful to someone.  God Bless,  Marc

[Darkhorse]

Here is a simple, practical test to see how close your lock is to being balanced. Put that UNLOADED rifle on a benchrest and solidly bed the rifle into the bags, or whatever, then take a good sight on the bullseye. Now set the trigger (if  you have set triggers) and check that your sights are still centered on the bull. Gently squeeze the trigger then check your sights. If they are still on the bull then your lock is fine. Nothing needs to be done to the frizzen spring.
If your sights are off the bull then that is where your ball will impact the target, and depending on your needs and desires it is probably time to do something about that frizzen spring.
Consider also that the barrel movement will be greater offhand than off sandbags meaning larger groups.

[jerrywh]

 Dark horse. There is a lot to say about that also. I had a lock that had a very strong mailspring and it always shot low off hand especially. The mainspring was so strong it would knock the gun down just enough to make it shoot low.

[Darkhorse]

I agree Jerry and I think perhaps a better job  could be done with a little mainspring tweaking also. If I was still a match shooter I would be exploring that also. But, now I'm mainly a hunter and home range plinker.
10 or more years ago I was hunting turkeys with my .40 flinter and called up 2 gobblers shortly after dawn. One was a really large bird and I had him at 30 yards and they had no idea I was there as I was hid well in the roots of a huge oak. I cocked my rifle and to my horror the mainspring just broke in half. Since then I want my mainsprings strong and untouched, even though in this case it was bad heat treating, I still hesitate to alter my mainspring in any way if at all possible.
Luckily I've been able to get good results without doing anything to the mainspring.
But really the lock is a system and several things will affect any one thing, so all must be considered.

[Pennsylvania Dutchman]

A lot of good info here! Thanks to all who replied.
Mark

[PluggedNickle]

I would say your frizzen spring is a little stronger than neccesary. My interpretation of a lock that's imbalanced is when the trigger is pulled the entire lock jumps and moves your front sight off target. This is more easily seen on a rifle with set triggers. This is a condition I remedy as soon as I've determined it's the problem.
I clamp the frizzen spring in a vice and using a dremel tool I grind the top surface following the original contour as much as possible. Great care must be taken not to overheat the spring to where it changes colors. I make several marks with a majik marker along the length of the spring and measure at each mark with dial calipers and by checking each mark I can remove an equal amount from each spot. When the spring weight is where I want it I put a buffing roll with buffing compound in the tool and polish the surface I've ground thoroughly. I will remove all the grinding marks to get a smooth surface. The smoother the surface the less chance of a crack starting.
I want my frizzen to open at 3 pounds or a little less, checked with a trigger gauge hooked on the top of the frizzen. I never touch the mainspring as I want it strong and fast.
BTW the first thing I do is thoroughly polish the entire lock to include straightening the lockplate. Check that the frizzen screw is not too tight and that the side of the frizzen isn't rubbing the barrel. If after all this the problem persists I will consider thinning the frizzen spring.
Others may do things different but I get good results with this method.

Great advice Darkhorse! 

[Rolf]

For the springs to be in balance is a good sounding theory. From personal experience it is my opinion that the main purpose of the frizzen spring is to keep the powder from dumping out when the gun is carried. Also it tends to keep the powder dry to some extent but not very efficiently.
   When it comes to tuning lock try this some time.  Take the frizzen spring off and fire the lock to check the sparks. You will see that it will spark much better with no frizzen spring. When I started out I made all my own locks because there weren't any to be bought. So I learned a lot by experimentation.  So how strong must a frizzen spring be?  It must be strong enough to stop rebound and keep the powder in the pan. It must be weak enough to allow total exposure of the powder when fired. That's about it. The main spring should be strong.

Thanks for a simple explantion. I'm working on the frizzen springs for the scratch built 1772 locks. Been wondering how to know when the spring is strong enough.


Best regards
Rolf

[Bob Roller]

IF the scrape marks on the face of the frizzen go all the way down from the strike point
to the low edge and there is no bounce or rebound that ought to work.Usually if there
is no rebound and the gun fires it's a good thing as well.The ideal geometry would be
to have a swift "slicing"motion of the cock against a frizzen that has a curvature to
accommodate it.I watched a film clip of a Brown Bess that had this geometry and the
cock was slow off the start but the sweep across the frizzen face nearly produced flames
instead of sparks.Tom Dawson's Manton 16 bore rifle had this geometry with an abrupt
slice and strike that rolled white hot sparks into the pan that had a bit of dwell time that
was observable and displayed the quality of the lock and the skill of whoever made it.
The variable would be the length and quality of the flint.

Bob Roller