touch hole waaayyy to low

[draken]

A while back I aqcuired a smoothbore flinter at a gun show that  has the touch hole located at the very bottom of the pan.  The vent liner has a screw slot and I can probably get it out, but is there any way to raise it?  There is about 3/16 inch of barrel flat left above it.   Is the barrel salvageable?

[bdixon]

Perhaps a larger outside diameter liner could be installed, but I am not sure if that will raise the hole far enough to completely correct it??  A few variables come into play here.  Re-drilling with the center higher,  enough metal at the bottom of the new dimension for threads, etc.

[rich pierce]

I'd drill and tap for a larger threaded rod (make it tight), leave a little sticking out, smack that with the ballpeen hammer to upset it, finish that off smooth, drill the touch hole where you want it, and cone internally using Tom Snyder's little tool.

[Jim Kibler]

If the touchole liner is quality I would likely do nothing.  It seems I remember Larry Pletcher's work concluded that there was no significant difference in ignition time with the hole as low as possible.  Seems this is one of those ideas that may tend to live on.  Perhaps Larry will comment.

[Stophel]

Yeah, have you shot it yet? Is it even giving you any problems?

Oh, how many old guns there are that have touch holes at the very bottom of the pan!   

[Mike Gahagan]

Depending what kind of lock it is,you could deepen the pan with a milling machine.You could even use a dremel tool with a burr.

[Larry Pletcher]

If the touchole liner is quality I would likely do nothing.  It seems I remember Larry Pletcher's work concluded that there was no significant difference in ignition time with the hole as low as possible.  Seems this is one of those ideas that may tend to live on.  Perhaps Larry will comment.

I agree with Jim here.  Two sets of experiments confirm to me that a low vent, even when the prime covers it completely, does NOT slow ignition speeds.  The links below give both photographic and numerical data supporting this.

http://www.blackpowdermag.com/featured-articles/part-6-high-and-low-vent-experiments.php

http://www.blackpowdermag.com/featured-articles/post-2.php

Keeping the vent squeaky clean and priming close to the barrel are far more important to ignition speed than vent height.  I could include a photo that graphically shows the strength of the flame entering the barrel with a low, covered vent, but it is included in the last link.

This is one of the myths in our sport that dies hard.  The one that says the pan ignites before the flint stops moving is another.  We have 80+ slow motion videos that dispell this one too.

Regards,
Pletch

[cmac]

A home made touch hole liner or an allen head liner would be my solution, but I agree with dishing the pan more also. The allen head liners are nice because they have a double venturi effect. If you did use one of these you might end up working the pan down also.?

[Tom Cooper]

If the touchole liner is quality I would likely do nothing.  It seems I remember Larry Pletcher's work concluded that there was no significant difference in ignition time with the hole as low as possible.  Seems this is one of those ideas that may tend to live on.  Perhaps Larry will comment.

I agree with Jim here.  Two sets of experiments confirm to me that a low vent, even when the prime covers it completely, does NOT slow ignition speeds.  The links below give both photographic and numerical data supporting this.

http://www.blackpowdermag.com/featured-articles/part-6-high-and-low-vent-experiments.php

http://www.blackpowdermag.com/featured-articles/post-2.php

Keeping the vent squeaky clean and priming close to the barrel are far more important to ignition speed than vent height.  I could included a photo that graphically shows the strength of the flame entering the barrel with a low, covered vent, but it is included in the last link.

This is one of the myths in our sport that dies hard.  The one that says the pan ignites before the flint stops moving is another.  We have 80+ slow motion videos that dispell this one too.

Regards,
Pletch

You cannot argue with the numbers, it may be that it looks bad, but functionaly there is NO ISSUE.

[rich pierce]

I think that in sloppy or humid weather a very low touchhole might be harder to keep clean and clear after a few shots.

[D. Taylor Sapergia]

I once moved a vent hole rearward and up a little.  It was in a Lyman GPR with a 1/4" approx. metric liner.  I moved the hole with an end cutting mill of 5/16" dia., then drilled for the 3/8" WL liner and threaded it 3/8" x 32.  It was quite a bit of work for aesthetics alone.

[draken]

Thanks for all the input, guys.  I opted for deepening the pan about 1/16 inchwith a dremel tool.   The lock mainspring feels rather weak too.   I wedged a tiny tiny piece of hardwood into the inside bend.   Only way I know of to beef up a mainspring.

Anyway, dumped 50 grains of 3f down the barrel, primed the pan and touched her off.
BOOM....................it works!!

[Dphariss]

Thanks for all the input, guys.  I opted for deepening the pan about 1/16 inchwith a dremel tool.   The lock mainspring feels rather weak too.   I wedged a tiny tiny piece of hardwood into the inside bend.   Only way I know of to beef up a mainspring.

Anyway, dumped 50 grains of 3f down the barrel, primed the pan and touched her off.
BOOM....................it works!!

If the spring is properly tempered polish it so temper colors will show.
Degrease.
Clamp the "bend" in a vise and then use a plier or vise grip to grip it out toward the end.
Flex spring to the desired point, an extra 1/4" should work, and then heat along the length of the with a propane torch.
KEEP THE FLAME MOVING. Apply a little more time to the thicker sections of the spring but try to get an even heat.
When the color comes to the bright blue the spring with suddenly relax, or should. Don't increase teh bend but IMMEDIATELY remove the heat and allow to cool for a minute or so. Spring should now stay at the new arch and should solve the weak spring problem which is often too little preload on the spring.

Dan