touch hole position

[sloe bear]

 just a quick question, what is the best placement for the touch hole? in my older rifles the touch hole is located at the bottom of the pan, but I've read some blogs that say to locate it towards the middle of the pan? what is the best place and why?

[Dphariss]

Best in middle of the barrel flat if the lock is set with the top of the lock at the centerline as well.

Should be no higher than this. Lower is OK I guess, I consider this about ideal. Placing the vent too low and cause erosion of the pan


Dan

[SCLoyalist]

There are a couple of articles, including ignition timing data, on Pan/Vent placement over on Larry Pletcher's blackpowdermag.com site. The test results are pretty well summarized by dpharriss' advice.

[t.caster]

This thread should be in the Gun Building Section. Shouldn't it?
I agree, centered at the top of the pan, and dare I say....never at the bottom.

[Dave B]

I know that my hunting rifle initially had only a simple touch hole but it was fairly fast. After watching the H House video his stainless touch hole made me want to improve the speed and so I drilled, tapped and installed a 1/4" touch hole liner. but My perceived ignition speed seem slower.  I am looking forward to trying  my new touch hole counter bores I picked up from one of the fellows here.

[dagner]

  if you have room one of the white lightning 5/16 or 3/8 from chambers they have gaint cones in the rear of ss steel liner  also cuts way down on missfires   i think they also make  1/4  bigger the better . all the big time flint shooter i know use and recomend them
dag

[James Wilson Everett]

Guys,

I position my flash hole center to be at the same level as the top surface of the top of the pan.  Another way of describing the position:  If you sight along the exact top surface of the flash pan towards the barrel side, you should only see 1/2 of the flash hole.

To have the flash hole slightly higher is OK, but to have it lower leaads to slower ignition, at least that is my experience.  You see, the flash of the burning pan powder ignites the main powder charge, and this flash moves very quickly the 1/4 inch or so from the flash pan to the main powder charge.  Listen to a well made flintlock gun go off and you may hear the click of the flint striking the frizzen, quickly followed by the bang.  If you hear a click - SSSS - bang, then something is not working properly.  Surely we have all experienced those dreaded hang fires where you have time to recite the Gettysburg Address during the SSSSS! 

I believe what often happens is that the flash hole is too low in the pan, is filled with powder and acts like a short fuse to ignite the powder.  The quickest ignition is when the flash hole is open and clear to allow the flash to travel through to the main powder charge.  Liners simply make the path the flash travels very short, thereby quicker and more reliable, but you still do not position the liner hole at the bottom of the pan.

Looking at Dan's photo it appears to me that the flash hole is slightly higher than the top pan surface, and probably gives very fast ignition.

After all, we call it a flash hole - not a short fuse hole.

Jim

[Jim Kibler]

Lower is fine regarding ignition speed.  It can be completely in the bottom of the pan.  It's a myth that this will result in slower ignition speed.  Reference Larry Pletcher's testing.  His testing also proved that it's faster to have powder right against the touch hole.  The fuse effect slowing things down is not valid.  Actually I'm pretty sure he found ignition speed to be faster when priming was directly against the vent! 

[Bob Roller]

The flash hole shown appeared to be on a late and sophisticated English
gun. These things are stunningly fast. The old American long rifle with a
hole drilled in the side of a thick barrel wall is a "fuse" hole and gives the
flintlock a bad name to this day. Does ANYone today make these rifles
without a liner that puts the barrel charge next to the primeing?

Bob Roller

[Jim Kibler]

If I recall correctly, Larry Pletcher's testing showed that while a CLEAN straight drilled hole is slower than a coned one, it was only by 15-20%.  A straight hole is prone to fouling more, which will make ignition less reliable and likely slow it down.  Hopefully Larry will comment.

Bob,

Guess the dumb Americans didn't know how to make a flintlock that worked.  I know we all have preferences, but lets be realistic!

[Bob Roller]

I am realistic. If the charge in the barrel is 1/4" or more away from the flash,
as opposed to within .040 away,my own shooting tests show the old way is
slower. If old and inferior ideas worked well, I doubt if Manton and others would
have gone to the trouble of coming up with better and faster ignition.
There is also a reason Jim Chambers markets a substiture for a hole drilled thru
a barrel wall. I don't think the Americans were dumb but they took a gamblers
chance by drilling a small hole in the barrel with the then in use drill bits and I
wonder how many of them snapped off about half way thru the barrel wall?

Bob Roller

[Jim Kibler]

Bob,

You might want to review Larry Pletcher's data on straight holes versus coned holes as far as timing goes.  He is timing these events very closely with a computer and equipment that can detect very small differences.  The human ear is very inqdequate in comparison.  As I indicated above, there is not as much of a difference as one might think for a clean hole.  Can a hole be cleaned between shots?  Yes.  Does a coned hole stay cleaner.  Yes.  Is a coned hole lined with a durable material superior to a straight hole.  Yes.  Can a straight hole work very well and be perfectly adequate.  Yes.  Frankly, I get a little frustrated with the mindset that anything other than 19th century British work is subpar and inadequate.  Views such as this generally come from ignorance and being close-minded.  This isn't meant in a condescending way either.  Just how I see things...  Nothing personal either. 

Jim

[Bob Roller]

I don't need a fast camera or a timer to tell me I had to hold thru longer with a
traditional American flintlock rifle than I did with Tom Dawson's 16 bore Manton
rifle. Also who ever surpassed the 19th century British work on locks?

Bob Roller

[duca]

Hi all, just wanted to add my 2 cents. What about Touch hole placement in front of the Breach plug. I have seen some with the Touch hole drilled into the plug a bit and the face of the plug filed some what like a cone to allow powder there. I would say that the Best placement would be for it to fall right in front of the Breach plug. I built a rifle and drilled the barrel and have very fast ignition. I also coned the in side of the hole a bit  to bring it closer to the pan.

[Larry Pletcher]

Regarding vent placement, I ran these tests when Gary B. related that he had seen originals with low vents. That got me wondering. What I found was that low vents did not slow ignition. Low vents were within .001 second of a level vent.  In fact where the powder was placed in the pan, made a much bigger difference. As long as the priming was close to the barrel, vent location was statistically insignificant. In these tests I positioned the priming up against the barrel with a rounded pencil eraser. When doing the low vent the priming covered the vent, but I tried not to fill the vent.

Trying to explain the experiment in one paragraph is not a good plan. The link below should explain it far better. I did this as a 6 part study; the link is to the introduction.

http://www.blackpowdermag.com/featured-articles/pan-vent-experiments.php

One last thing. If you use a liner that places the barrel charge close to the pan and you prime up against the barrel, the two charges are perhaps .030" apart. IMHO two charges this close together ignite as one charge. ( Try placing 2charges in a sheet of paper with a feeler gage of .030" apart. Remove the feeler gage and try to ignite one charge without without igniting the other.)

Regards,
Pletch