Lyman GPR Flash Pan

[scatteringlead]

I have just completed a Lyman GPR kit and I have noticed that the flints strike the pan on the outside edge. This happens with 5/8 and 3/4 flints. If I use a shorter flint it seems to strike the frizzen a little lower than than optimum for good sparking. Is there any disadvantage to making the pan a little longer (grinding a larger powder tray)? Has anyone else had this problem with their GPR.Any responses would be appreciated.

 

[jim gray]

I have noticed that the flints strike the pan on the outside edge.

I think you mean the frizzen instead of the pan. You should be able to fix this by adjusting the flint in the jaws. My GPR came finished, but it seems to me that you could correct this problem without altering the flashpan.

 

[CoyoteJoe]

I have a T/C flint which is very similar. I think these locks have a rather poor geometry. If you set the flint to just clear the frizzen at half-cock, which is normally as it should be, then the flint will strike the pan and chip the corner off the flint.
I never tried to correct it, just live with it by setting the flint a bit farther back, which does reduce frizzen contact, or set it back and turn it bevel down, which improves frizzen contact but reduces flint life.
Or use a more narrow flint. There is not 3/4" between the barrel and the inside edge of the pan, about .700" so a 5/8" wide flint should just clear, but 5/8" flints are usually too short to set well out to the frizzen so you still don't get there.
Just a defect you have to work around and compensate for as best you can. :results:

 

[RussB]

I'm thinking he probably means the pan, as the last one I built seemed to do the same. I just "choked" up the flint a bit into the jaws, until the hammer would rest without the flint touching the pan.....there is already some "damage", ie, small nicks, on the outside of the pan before I caught it.

I'm not sure how this is going to affect firing it yet. I still get plenty of spark, but the frizzen does not open completely.

Russ

 

[RussB]

Sorry Joe, I guess you posted while I was typing.

I think your take on this is about right.

Russ

 

[jim gray]

Oops, I guess your right, Russ. The pan on mine seems fine, maybe shorter flints would help too.

 

[Stumpkiller]

If you set the flint to just clear the frizzen at half-cock, which is normally as it should be . . .

To go a little further with what CoyoteJoe said, there is no signifigance built into where the flint should be at half-cock so long as it is clear of the frizzen. It just usually works out that close to the frizzen at half-cock is good, but it will help to know why.

What matters is at full forward the flint is pointing at the center of the pan (in line with the vent), and on the way down it should contact the maximum run along the frizzen face possible. FOr safety, it is also very important that the heel of the frizzen clears the flint when snapping the frizzen closed with the hammer at half cock. If it's too close and strikes the flint, you have an accidental discharge! :shocking: With some locks this can happen when you tighten the flint in place so that it is touching the frizzen at half-cock. The horizontal distance between the frizzen pivot/screw and the hammer pivot/screw, and the curvature of the frizzen face will effect the best flint length.

A well designed lock has all the geometry in place so "just clearing the frizzen at half-cock" is fine. But frizzens get replaced and locks get mass-produced, etc. Always good to know why to do things instead of just how.

Generally, the flint should be as wide as the frizzen. Less can gouge the frizzen and more can strike the barrel or pan edge, as in your case.

 

[CoyoteJoe]

Hey, happens to me all the time. I type so slowly and take so long to compose my thoughts and correct my typo's that by the time I get it posted it is already redundant!
But who cares, I got :m2c: in anyway!

 

[Old Charlie]

My GPR dose the same thing. I also already have some dings on the pan outer edge. The frizzen is suppose to be 3/4 but is only 5/8 in. I think I will just knapp (break) the outer edge of the flint so it will not hit the pan.
Old Charlie

 

[2172]

Stumpkiller...good point..I have a nice tattoo from the accidental discharge caused when my cocking the gun caused the flint to strike the frizzen on the upstroke. I was pointing down range, and was on the firing line having just primed, but I had on a tee shirt, and my bicep now has an interesting polka dot pattern...Hank

 

[scott k]

I just purhaced a trade gun witch is the same lock as the gpr and had a similar situation. A cut agate only fit with the bevel up or it fit the flash pan. The end of the tumbler is used as the cock stop and is where the casting sprue is. It looked like they cleaned a little to much off.I added some steel to the stop by welding so it does not go down so far on mine. Most 3/4" hand knaped flints now fits. Longer one's need some knaping so frizzen closes.
Lehigh...