Lock Geometry Question

[QuanLoi]

A couple of years ago I built a rifle around a Davis Late English flintlock.  Mounting a flint bevel up in the jaws of the cock points the edge of the flint a little over half way above the center of the frizzen.  After use, as the flint is knapped, the flint strikes the frizzen lower still.  Flipping the flint bevel down points the edge above and forward of the pan, so that is not an option.  As a result, I rarely shoot this gun as flint life is rather short... (I save the flints and use them on my other locks).  Im wondering... is it possible to modify this lock?   

[smallpatch]

Need photos!

[Mike Brooks]

A couple of years ago I built a rifle around a Davis Late English flintlock.  Mounting a flint bevel up in the jaws of the cock points the edge of the flint a little over half way above the center of the frizzen.  After use, as the flint is knapped, the flint strikes the frizzen lower still.  Flipping the flint bevel down points the edge above and forward of the pan, so that is not an option.  As a result, I rarely shoot this gun as flint life is rather short... (I save the flints and use them on my other locks).  Im wondering... is it possible to modify this lock?   

I use that lock with the flint bevel down. It is very fast even though the flint points just ahead of the pan.

[QuanLoi]

Bevel up:




Bevel down

[Hungry Horse]

Well, for starters the flints in the pictures aren't all the way back in the jaws of the cock. I usually knap a notch in the heal of the flint with a small knapping pin, and cut a hole in the leather wrap, to lock the flint in place. As flint wear the often swivel one way or another if they aren't secured.

  Hungry Horse

[okawbow]

I use thin 5/8" flints in that lock and get around 25 shots before I need to knap the edge. I put them in bevel down.

[smylee grouch]

I have that lock on my 62 cal. and I use a more square flint. I some times have to knapp the back end of the flint to fit far enough to the rear in the jaws but with a notch in the leather and flint I get twice as many shots out of a flint and it is very fast.

[rich pierce]

Yep need to get that flint back snug against the top jaw screw. Nice looking gun!

[Mike Brooks]

I don't use flints as thick as the bevel down flint you're using.

[QuanLoi]

I apologize if I didn't make myself clear in my first post.  Moving the flint back further would enable it to strike the surface of the frizzen even lower.  The thickness of the flint doesn't change the point of impact to the frizzen if mounted bevel up.  I think I already know the answer to this, but is it possible to change the cock or modify it so that the flint, if mounted bevel up, strikes the frizzen at a higher point?  I think, based on the design, the answer would be no.  But there are lock makers and individuals on this site that have a lot more knowledge than me, so...

Thanks in advance...

[EC121]

It is possible to start heating and bending things, but who knows where that will end up.  Probably mess up more than it will fix.  Order a spare frizzen and cock or even another lock to experiment on and save the original parts.

[Hungry Horse]

Part of the problems you are encountering are inherent in late flintlocks, with short throws, and waterproof pans. The shorter throw often leads to a lower contact point on the frizzen, and the waterproof pan presents a smaller target for the sparks. I have not been successful in fixing these shortcomings by altering the cock, although someone other than myself might. I have had positive results from heating the top half of the frizzen, and curving it back towards the cock a couple of degrees. Unfortunately this requires retempering the frizzen, which is a whole other issue.
 Guns of this period with high end waterproof locks were often the property of the wealthy, and rarely were subjected to long strings of shots like we expect them to endure today. Also, the wealthy didn't care about flint life, and likely changed the flint whenever the gun was cleaned and stored, no matter how many, or few, shot it had experienced.

 Hungry Horse

[hanshi]

Yes, the flint should be solidly mounted against the cock screw or at least have something behind it to keep it from moving.  Bevel down often causes the flint to strike the frizzen head on.  This can result in very short flint life and/or gouges in the frizzen face.

[sqrldog]

Guys I may not know what I'm talking about but I have shot flintrifles for many years. I have bever had to seat a flint against a screw to get a flintlock to work properly. Often locks are picky about the size thickness and length of flint and yes I have notched the rear of a flint to use a flint that was a little too long. As flint wear and are knapped I often move the flint out to keep the flint contacting the frizzen about a third of the way from the top of the frizzen. Often continuing to use a flint that doesn't touch the screw. Often its a matter of trying several flints and then bevel up or bevel down to find the righ combination. Tim

[Scota4570]

Interesting problem.  Maybe it can be tuned?  Why not modify the cock by stretching the goose neck to make a longer throw.  If the rest position of the cock is to high after firing, adjust the stops on the cock and tumbler. 

[Mike Brooks]

Interesting problem.  Maybe it can be tuned?  Why not modify the cock by stretching the goose neck to make a longer throw.  If the rest position of the cock is to high after firing, adjust the stops on the cock and tumbler.

In my personal experience with this lock,  flints of the proper size/shape  will give you exceptional performance, no lock modifications are needed.

[D. Taylor Sapergia]

I agree with Mike.  This is a great little lock and is very quick and sure when the right flints are used.  At the risk of offending, those flints are much too thick and short.  When a flint starts to wear down, I move it forward and place a twig between the flint and the top jaw screw.  This gives some backing and keeps the flint from wanting to rotate.  If the flint is not held absolutely solidly, energy is lost and the flint becomes ineffective in producing sparks.  I lost a postal match shooting against Neil Hunter once, for that reason.  If you don't shoot tens against Neil, you'll lose every time.  Lesson learned.

[QuanLoi]

There's no offense taken.  It doesn't really matter how thick the flint is if mounted bevel up.  And I have to agree with a previous post about it not being necessary to back the flint against the screw.  Actually, as a flint wears, I tend to move it forward toward the frizzen while at half cock.  I use a notched leather in the cock and I've never had an issue where the flint rotates after tightening it down.  However, I understand there are different opinions about this particular lock.  My original question was about the feasibility of modifying the cock...  and I guess I'll live with what I've got.