First oil the pivot screw/pin at the front of the frizzen to make sure that the frizzen is opening and closing easily.
Then, remove the frizzen from the lockplate( you probably will have to remove the frizzen spring first), and check the bottom of the " cam"- that small projection below the flashpan that makes contact with the upper arm of the frizzen spring. The two contact surfaces should be mirror smooth, and oiled. Do that first before going any further with any modification of the frizzen or spring.
If the frizzen is still resisting the flint, usually this occurs because the upper arm continues on a straight line, and to the rear of the lockplate from where the contact point of the cam to the arm occurs. The cam has to " climb a mountain", compressing the spring arm further, BEFORE the frizzen can pop open.
a. By reducing the height of the cam, you can reduce the amount of pressure of the frizzen spring on the cam, and lighten up the tension of the spring on the frizzen. The Frizzen spring is also known as a " feather " spring, Because ITS ONLY FUNCTION is to keep the frizzen closed when the barrel is pointed down to the ground. This is a very sensitive job to perform, and for that reason, unless you are very experienced, and patient at doing fine polishing work, I don't recommend this method of " fix".
b. By heating the spring arm up to soften it, you can bend the upper arm so that it flattens out just beyond or to the rear of the point of contact with the cam. Then you have to heat it up to reharden it, and then you have to temper it to get it to function correctly as a spring. Because most people don't have the equipment or skill to do this kind of Annealing, Hardening, and Tempering of springs, I don't recommend this method as a " fix", either.
c. What I do recommend is grinding a small dish in the spring immediately to the rear of point of contact by the cam to the upper arm of the spring. The dish does not have to be very deep. I don't go deeper then 1/4 the thickness of the spring arm at that point. A couple of thousandths of an inch of metal removed is enough. I don't even use a grinding bit, but rather a sanding disc on my dremel tool to do this stock removal method.
Mark the spot there the Cam touches the spring when the frizzen is closed. Draw a line on the side of the spring arm reflecting this location, in case you remove the line across the spring's width while sanding and polishing.
The purpose of the dish is to allow that cam to swing out into open air, for must a small portion of a second, so that the frizzen opens before the spring arm comes back up and stops the cam from moving rearward.
All sanding and polishing has to be done with the long axis of the spring arm- never sand or file across the spring, or you will create a weak spot that will eventually fail and the spring will break. When I am sanding in that dish, I put my thumb nail right at the Line I made across the spring where the cam contacts the arm when the frizzen is closed. This keeps the sanding disc from moving too far back, unless I want it to. I want the edge of the dish to begin just at that line. The dish is maybe 5/16" across, and .005-.008" deep. You do have to check this by trial and error, as each lock is different, and some are going to need more or less metal removed to achieve the result.
I also reduce the width of the contact point of the bottom of the cam where it rubs against the spring arm. I am talking a surface that may be flat, but is only 1/32" wide at most. I want the frizzen to stay closed when its suppose to be closed, and not open when you shake the gun, or bump the gun. But, I also want it to open with no more than 3 lbs of tension on that frizzen. ( see my article on this forum on Shooting and Tuning Flintlocks where I describe how to test the tension weight on a frizzen. ) The width of that contact surface of the cam is largely going to determine how hard or easy it will be to get that frizzen to move enough to swing out over that dish. You can take a cam down small enough to have only 1 lb. of tension on the frizzen, and the frizzen works properly every time.
In fact, the test for a well tuned flintlock involves removing the frizzen or feather spring from the lock entirely, and firing the gun without it in place. The weight of the frizzen, the angle of its face, and the angle of contact with the frizzen should be enough to cut the sparks needed, and throw both the frizzen open, and the sparks down into the pan.
The benchrest flintlock shooters don't even put feather springs in their locks, because they are never needed. Think about what they are doing. These are target shooters, shooting long, heavy barreled guns. You are not allowed to prime your gun until its pointed down range. Only when the barrel is pointed down range, and the range is declared safe and open are you allowed to prime and fire. The gun is mounted on a bench rest. The frizzen is not closed until the priming powder is put into the pan.
These shooters will often put a piece of leather washer between the lockplate and the frizzen, on the pivot screw/pin, to slow the movement of the frizzen when it rebounds after opening.( this prevents the frizzen from striking the top of your flint hard enough to break the flint!) But that washer does not offer any resistance to the frizzen being popped open when the gun if fired. ONLY the weight of the frizzen( Less than 8 oz.) the angle of the face, and the angle of impact of the flint to the face, along with gravity( reflected not only in the weight, but by any inertia to the frizzen moving upward) cause any delay to the frizzen popping open on Bench rest flintlocks.
If you lock is tuned properly, it will creates sparks all day long to ignite your priming powder. Once the angles are met, all you will see is scrape marks along the face of the frizzen, but not gouges, PROVIDED that your flint is not loose in the jaws, or that you are not using too soft a material as a flint wrap. Soft materials act like a shock absorber, and can produce tiny chatter marks on the face below the highest point of contact of the flint's edge to the face of the frizzen.
The main benefit of reducing the tension of the feather spring on the frizzen is lengthening flint life. At the cost of flints these days, its becoming a factor in how many times you can shoot your gun. That, and the price of Black Powder. I expect flints in a well-tuned lock to give me 100 or more strikes before they have to be replaced. Some give more than 120 strikes, and occasionally we hear of a flint giving more than 150 strikes before it has to be replaced. When you compare those numbers to that which was expected of a Brown Bess musket, where a new flint was provided with every " cartridge" box of 20 rds, there is a substantial difference in performance of the locks.
Paul
