That flash hole is low but shouldn't be causing ignition problems. My first longrifle was the Traditions Pennsylvania Longrifle. I had a hard time getting some good reliability out of it because Traditions uses that darn tiny lock on it. It's actually the size of pistol lock and is much smaller than locks used on longrifles at the time. Below is a shot of mine. By the way I pickled the barrel to make it look old, which is why it's not blued. It's a Hershel House technique that a gunmaker in our reenactment group helped me with.
Anyhow, you can see below that my flash hole is also a bit low, but not as low as yours. Ideally it will either have the center of the flash hole even with the top of the pan or slightly above. That lock also ate flints until I found out why and fixed it.
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Compare the size of that pan with the one on my L&R Queen Anne lock that I have on my Early Lancaster rifle:
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Now, because I'm familiar with the idiosyncrasies of that lock I can make it go off reliably. Part of the trick with that lock is to only fill it half full with 3F powder. Then close the frizzen and while holding the wrist of the rifle, snap your wrist to the right in a sudden rocking motion. Then open the frizzen and look at the powder. It should be banked on the far side of the lock with an empty space next to the flash hole. That empty space allows the flash to travel across the pan unimpeded and into the flash hole and that's the key to getting it to flash quickly and stay away from the dreaded Sssshhhhh BOOM! Hollywood film effect. It becomes second nature after a while of closing the frizzen and snapping your wrist to the right. If you fill that tiny channel with powder, the flash has to burn through it to get to the flash hole.
If you really want to surprise yourself, lick your finger and stroke it through the pan. Then fill the pan with powder and dump it out. Because you wet the pan slightly, small grains of powder will coat the pan. Close the frizzen and fire the rifle. It will go off perfectly fine with just that thin coating of powder adhering to the bottom and sides of the pan. The worst thing you can do with that lock is fill it up to the top, so don't - half-full; close the frizzen; snap your wrist to the right. You're ready to shoot and it will go off virtually every time if you load it that way.
Different locks require different things and half of the fun (and most of the frustration) is figuring out what your gun likes, needs, or wants. The longrifle I use now is an Early Lancaster rifle with a 44½" swamped barrel that is 60" long overall and about 2-lbs lighter than my Traditions longrifle. It has an L&R Queen Anne lock on it. It is a much larger lock than the traditions and it has a pan about 4 times larger than that. Doesn't matter with that lock at all whether I put in a little powder, a lot of powder, bank it to one side, or whatever. It just always goes off. There is a bit of pride though when you figure out an idiosyncrasy with a temperamental rifle that makes it fire reliably for you...but not just anybody can pick it up and make it work.
As I mentioned earlier, I had a real problem with this lock eating flints or even breaking them. There's not much difference in this lock between putting the flint too far forward and putting it too far back. Too far forward will smash the tip of the flint and flatten it out. Too far back and the flint will actually slap against the frizzen and break a chunk of the underside of the flint off. At the correct angle the flint will slice along the frizzen scraping offsuper-heated shards from the frizzen (sparks). When you get the right angle on where the flint strikes the frizzen, you will suddenly get 80 to 100 strikes or more out of one of these small flints. The trick is to set the flint up so that it strikes the frizzen at a 55° to 60° angle. To check this, first of all make sure there is no powder either in the pan or in the barrel (safety first, last, and always!). Then to see the angle it is striking pull the cock into full-cock position and close the frizzen. Then hold onto the cock with your thumb, pull the trigger and slowly lower the cock until the flint touches the frizzen. Take a look at the angle and decide if it's too little angle, too much angle, or just right. the frizzen is curved, but if you draw a line straight up from where the edge of the flint contacts the fizzen and then look at the angle the flint hits that line, you can make reasonable adjustments. It really is a Goldilocks adjustment. Here's a chart to help you get in the neighborhood of the correct angle. The magic seems to happen at a 55° to 60° angle for almost everyone:
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When you get your flint around this angle your flint will not only last a very long time, but it is self sharpening and you won't find yourself knapping it all the time like you will if you don't pay attention to this angle. You may find the angle that works on your lock is slightly different from this but it won't be by much. There are very simple indicators if you have the angle too steep or too shallow. If it's too shallow you will crumble the edge of your flint and find out you have to sharpen your flint by knapping it. If it's too steep, the top of the flint will slap the frizzen instead of the edge of the flint hitting it and you will knock a big piece(s) off the bottom of your flint. So adjust it as needed, but odds are it will be within that 55° to 60° angle.
If I recall correctly that lock uses a 5/8" flint. I think it calls for a 5/8" wide by 3/4" long flint, but I had a lot of trouble getting the flint back far enough to get the right angle with the 3/4" length. If you run into that, a simple solution is to use a thinner leather pad to hold the flint. If that is still not good enough, fold the leather pad you use to hold the flint in half and then cut a "V" notch in the folded edge of it. This will give you a diamond cut that will let you move even farther back because the leather won't butt up against the cock screw that is used to tighten the jaws.
If you need to move the flint forward a fair amount to get that angle, either use a thicker leather pad or put a twig behind the leather flint pad to help keep it from slipping back. I believe I just ended up ordering the 5/8 "x 5/8" flints from Track of the Wolf for it back then. As long as the flint is positioned correctly and I flick my wrist to the right after half-filling the pan, it became a reliable shooter. It was also very accurate but required a heavy load (95grs.). I think my barrel from about 2003 or 2004 is longer than the current model. The barrel on mine is 40¼" long and I think the current model has a 38" or 39" barrel/ You'll have to work up your own load for accuracy once you get it firing reliably all the time.
Hope that helps,
Twisted_1in66
Dan