The biggest culprit in slow ignition speed in the flintlock is the Touch hole. There is also a lot of theory, legend and myth associated with this subject.
For instance; “Bank the powder away from the TH for faster ignition and to prevent the fuse effect” So, is this a myth? “Not necessarily”
How about a legend? “Again, not necessarily, but it most likely is.” Confused yet? More on this later.
In an earlier post I described a new shooter being overwhelmed by the all the neat stuff going on in front of the eye and the noise “ Ker-latch ssssssss Boommmmm. In truth this is noise most shooters hear and is fairly accurate to the new gun. But if your gun sounds like that then it’s really sloooooowww. What it should sound like is this; “ ch..BOOMMMMM!” The sound of the flint striking the frizzen and the main powder igniting should come so close as to almost be one sound.
When your rifle sounds like this then it’s close to being really fasssst!
Why is this? In the present time as in antiquity a lot of touch holes really were lacking in design. Below is an illustration of the typical production touch hole liner found in many rifles and in some custom guns.
Some are worse. The flash hole is often at the bottom of a screw slot. The touch hole size will be too small. And the cone will not be deep enough to serve it’s own purpose. Back in the day I reworked a lot of liners with this type geometry. The cone was enlarged and lengthened as deep as possible. The hole was drilled out to optimum size. And I would use a little ball endmill to cut out the very center of the screw slot down to the face of the TH (touchhole). Reason being, sometimes it’s just difficult for the fire to find the actual touch hole itself when it’s hidden by steel.
Below is an illustration of a modified TH liner.
I do the chamfer because MY theory is it helps direct fire into the flash channel.
Notice the enlarged cone. This gets a lot of main charge real close to the TH. Simple; The more powder your prime can ignite the faster your total ignition time will be.
The flash channel should be as short as possible and still leave a little flash hole length. I want mine under 1/16” long. This allows the fire to kiss more of the main charge at once and quickly.
When all this is done it’s time to go shooting. I fire a couple of shots to gauge the speed. Then using a set of number drills I drill out the flash channel one size at a time until I get the desired results. Number drills are small drill bits that are graduated in thousandths of an inch instead of fractions. For instance with regular drills if I go from 1/32 to 1/16” I am increasing the diameter from .032 to .0626 and the circumference is increased exponentially (too much).
With number drills I can increase the size by .004” and try it. Remember the circumference also increases and now you have much more surface area to ignite. Remember this also; “You can remove metal easy but it’s much harder to put it back on.” So keep those drills small.
Example: Jim Chambers excellent White Lightning TH liners comes with a .055 hole. For .40 and .45 I find that .062 works excellent. For a .54 where I want reliability and speed a good starting point is around .070. These actual figures depend upon your actual gun and TH liner geometry so experiment a little. Don’t make your hole so large that your main powder wants to self prime your pan. A couple of grains trickling out is alright. The smaller the grain (FFF) the smaller the hole.
Mr. Chambers liners also have a cone with radius shape to them. Like a shaped charge. Unfortunately these don’t come in removable versions or metric threads. Your barrel must be drilled and tapped, the liner installed, then the excess cut off and hand worked down to flush. It is very much worth putting out a few bucks to have this done.
A couple of years ago I fitted a liner from Rightnour to a new Pederosoli flintlock.
I drilled it out to .062 and I was really surprised at the speed of this rifle. Not to say it couldn’t have been opened up another drill size but still it was a surprise. The Pederosoli’s have a large lock with true flat springs instead of coil springs. Sparked really nice.
It’s been a couple of years since I bought one of these but order one or two and if they haven’t changed the design you will have the starting point for very fast ignition. These things already have all the mods done to them I used to do years ago.
How about the prime? Well timed tests show 4F is faster than 3F but I really, really doubt a human being can detect the difference. So if you’re out of 4F don’t stress yourself out, just use what you got.
Now back to the Myth/Legend of banking your powder. A fellow named Larry Pletcher has developed some cool techniques for timing anything imaginable that has to do with a flintlock and speed. He gives his data in a format right down to the thousandths of a second. His tests show that banking the powder against the vent is actually faster than banked away. How about that?
Before anyone gets into a lather over this sacrilege of legend allow me to explain something: His tests were done with a well designed TH with a predrilled vent. In a well designed vent it doesn’t matter where the prime is located. If against the vent then it simply becomes one with main charge causing instantaneous ignition.
On the other hand, how about the hangfires we ALL have experienced which cause us to shake the prime away from the vent, and which we know Ol Davy and Dan’l also experienced. Causing the legend we know and have experienced concerning banking the prime. Simple. Consider illustration #1 for a second. This long flash hole is really a tunnel. And when the tunnel fills with powder it must burn through that powder in order to ignite the main charge, which causes hangfires or delayed ignition (if it shoots at all). Hence the “Correct” thing to do is bank the prime away.
Now look at illustration #2. Notice the tunnel is gone and it now is a window from the pan to the main charge. Nothing to burn through. When the sparks hit the prime it all goes off right away.
And that is why I say; It both is a legend and is not.