Frizzen question

[elee]

Hello; Here is a question for all you hard core flintlock shooters. I recently purchased a new custom .54 flint rifle with a 1803 Harpers Ferry lock (repro, Davis I think) that the seller said been tuned and had a hardened frizzen. I have yet to shoot the gun, but I did buy some high quality 3/4" square black knapped flints to try out the lock. When I mounted the flint and snapped the lock, the flint broke into several large pieces. I tried a second flint. It too broke. Not chipped...it broke into three pieces. And then a third. Do any of you have any thoughts on why? Could it be because the frizzen is hardened? I own two other flintlocks, and have never had a flint(s) break like that before. Is it my own ignorance in using the wrong flints in a military style lock? A bad batch of flints? Any thoughts or suggestions would be greatly appreciated! Thanks
   Elee

[rich pierce]

Some Harpers Ferry locks are ‘bashers’ - they strike the frizzen head on instead of with a slicing action. One fix is to lift up the rear of the flint with a leather or twig shim. Be careful to make sure the top jaw or top of the cock will not strike the frizzen.

A more radical approach is surgical. Make a hacksaw cut low in the front loop of the reinforced cock, bend forward until it closes, then braze or weld it shut. This will change approach angle.

Hardness is less likely to break a flint than a frizzen too soft. On the hard one the flint glances. On the soft one it digs in and binds.

[Daryl]

Certainly sounds as if the angles are wrong.

[pilot]

Did you mount the flint bevel up or down?  You can change the impact angle by turning the flint over.

[elee]

Thank you for the replies. I suspect you are all right about the angle of the flint. When I received the rifle, it had a flint mounted in the jaws upside down with a very steep bevel that appeared to have have been modified with extra knapping. I was too dim to think about it at the time, but apparently there was a reason for that...the flints I mounted were right side up, with a long sharp bevel. Live and learn. Obviously I need to spend a little quality time with the gun in order to better understand what is required in regards to best flint and flint placement. Thank you all for your help!
    Elee

[Bob Roller]

Certainly sounds as if the angles are wrong.

That would be my diagnosis as well.Did you try the flint with the flat side down?
Bob Roller

[Daryl]

If the flint protrudes too far from the jaws, this will also reduce the arc of travel. A shorter flint
 might work better, but beware of the top-jaw's front edge (or screw) striking the frizzen first.

[Dave B]

Is it possible that he may be getting frizzen rebound and the frizzen is bashing the top of the flint at the point of the jaws causing the fracture?  You can test this by putting a piece of card stock on top of your flint and clamped by the top jaw just to see if your getting rebound contact.

[Daryl]

True!