Author Topic: Touch Hole I.D./Touch Hole Liner I.D.  (Read 6750 times)

BrushCountryAg03

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Touch Hole I.D./Touch Hole Liner I.D.
« on: March 12, 2013, 09:23:34 PM »
Howdy y'all,

I would really like to hear everyone's thoughts & opinions regarding the diameter of a touch hole whether it's drilled straight through the barrel or in a liner.  If you should choose to enlarge a touch hole, where do you draw the line between the speed at which the spark/fire travels from the pan to the main charge and the loss of too much pressure from the main chamber upon ignition?  I for one would be glad to trade a little velocity any day of the week for faster ignition along with better accuracy.

For example, I installed a White Lightening from Chambers on a pistol and although the the lock is fast and sparks extremely well, I'm still getting almost what sounds like a "fuse effect". 

My instinct is telling me that the touch hole I.D. must be smaller than it should be...Therefore, I want to enlarge it with a little bit bigger drill bit.  Is this a good idea?

Many Thanks,

Will

mjm46@bellsouth.net

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #1 on: March 12, 2013, 10:13:13 PM »
If you bought your White Lightening TH from a place like TOW it may have a very small opening, they are producing their own. The original WLTH that Chambers produces are about as small as you can get away with. They told me that they should be drilled to 1/16" at that size they work great.

Offline Greg S Day

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #2 on: March 12, 2013, 10:39:34 PM »
I always drill mine to 1/16".   Always seem to have good fast ignition.

Greg
He Conquers Who Endures

Joe S

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #3 on: March 12, 2013, 10:47:05 PM »
Larry Pletcher found that touch holes below 1/16” slow ignition.  Larger holes do not speed ignition.  Here’s a link: http://americanlongrifles.org/forum/index.php?topic=9365.0   Go to page 2.

Quote
If you should choose to enlarge a touch hole, where do you draw the line between the speed at which the spark/fire travels from the pan to the main charge and the loss of too much pressure from the main chamber upon ignition?

It is well known that larger flash holes reduce pressure, which is all well and good, except that no one I know of actually has any data that would substantiate this.  Do you have any? 

Quote
For example, I installed a White Lightening from Chambers on a pistol and although the the lock is fast and sparks extremely well, I'm still getting almost what sounds like a "fuse effect".

See Pletecher’s data on “fuse effect” at  http://www.blackpowdermag.com/featured-articles/filled-vent-test.php



BrushCountryAg03

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #4 on: March 13, 2013, 03:51:04 AM »
Wow Joe, thank you for those links to the vids...Seeing is believing and I had a lot more questions answered watching those than I was willing to ask. 

So based upon what I've learned, can I try the following: 

Drilling the touch hole out to 1/16" and then putting a slight cone to the outside of the touch hole without cutting into the web?

Offline Jim Chambers

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #5 on: March 13, 2013, 04:13:16 AM »
The really serious shooter who use our White Lightnin liners tell me they use them with the .055 diameter hole that comes in the liner.  After several thousand shots the hole will enlarge.  They say that after the hole gets larger than 1/16" or .062 they start to loose just a little bit of accuracy, and they change liners at that point.  Personally, I no longer play the extreme accuracy game.  I'm more into hunting and having the gun go off every time I pull the trigger.  I find that enlarging the hole to 1/16" gives me near 100% ignition, and I still get good accuracy for a couple thousands more shots.

Joe S

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #6 on: March 13, 2013, 04:50:38 AM »
External coning has no effect on ignition speed.

Here's Pletcher's data:

With no external cone, mean = 0.044 standard deviation = 0.032

With external cone, mean = 0.041 standard deviation = 0.028

There is no significant difference between these data sets.  These tests were performed with a barrel fitted with White Lightening liners.

Offline David Rase

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #7 on: March 13, 2013, 06:07:34 AM »
I have a Jack Brooks Type G trade gun with an external cone and I cannot tell any difference in ignition speed between it and my internal coned guns.  In fact, I gave externally coning my latest .40 caliber a lot of thought and studied Jacks external cone before I opted to use the internal coning tool I made.
David

BrushCountryAg03

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #8 on: March 13, 2013, 06:19:56 AM »
@!*%...How do I keep getting things like these wrong!  I have such a long way to go...Luckily I have you good folks to help guide me.

I do appreciate the help everyone.

mjm46@bellsouth.net

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #9 on: March 13, 2013, 03:17:02 PM »
Wow Joe, thank you for those links to the vids...Seeing is believing and I had a lot more questions answered watching those than I was willing to ask. 

So based upon what I've learned, can I try the following: 

Drilling the touch hole out to 1/16" and then putting a slight cone to the outside of the touch hole without cutting into the web?
SSS, If you' already have a Chambers WL Liner installed I would avoid trying to cone the outside of the hole. Those liners don't have a lot of material to the outside and if you try to cone the outside you'll likely totally enlarge the vent. Just increase the drill size to 1/16" and try it out.

Offline Keb

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #10 on: March 13, 2013, 04:05:21 PM »
I don't use liners and drill 3/32 vent holes with a small chamfer on the outside. I don't shoot competitively any more. Maybe that's why. I don't know.

Offline RAT

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #11 on: March 13, 2013, 05:25:13 PM »
A personal opinion... while touch hole liners can be replaced when they burn through over time, I think the main reason for them is that it makes it easier to cone the inside. David has a nifty tool (after an original) that can cone the inside of a hole drilled directly into the barrel, so it can be (and was) done this way, but it's easier to install a separate part that's already been coned.
Bob

Offline Dphariss

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #12 on: March 14, 2013, 04:26:12 PM »
Straight holes less than 3/32 are less reliable if there is much barrel wall. 3/32 was what was mostly used in the 1960s it would seem. But these are so large that its impossible to keep the charge in the barrel  and will self-prime if the vent is not blocked by the pan cover.

Vents with large external cones tend to flash when dirty so they need to be cleaned. They also are harder to cover with the pan cover
The flat faced, internal cone is the most reliable in the field. Its what the English settled on it would seem and they did the serious legwork in FLs and patented a lot of stuff, most of which was simply "stuff" but some, the Nock breech and the recessed breech by Manton had validity and perhaps some others did as well.
When it get cold, when it gets windy etc etc this is when the touch hole gets tested.
I tend to follow the lead of the English. Find a good Manton shotgun and look at the locks and vents. These are still state of the art. But remember that some were set up to self-prime.
The English spent a lot of time on speed, reliability and consistency since wing shooting was a big sport and poor performance would make this very difficult.
We have to remember one thing. The main charge is ignited by RADIANT HEAT. There is no flash of fire into the vent for any distance since the bore is SEALED when loaded and it would take considerable pressure to do this. The primer flash is very low pressure since the pan is open to the atmosphere. So the more heat the main charge "sees" through the vent. The closer the charge is to the pan the more heat it sees. Larger vents work the same way. But a vent like this

Is pretty hard to fault.
I tend to build my own liners similar to WL
Dan
He who dares not offend cannot be honest. Thomas Paine

BrushCountryAg03

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #13 on: March 14, 2013, 09:33:12 PM »
That's interesting, especially taking into consideration, wind, cold, & precipitation.

Offline Dphariss

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #14 on: March 15, 2013, 07:36:37 AM »
I put a vent liner in a barrel and for the heck of it left the vent at the pilot hole size of .040.
Shot the rifle with no regard to cleaning the vent loaded, primed, shot. It flashed in the pan on shot 10.
Had I did a little cleaning It likely would have worked as well as anything.
I left it .040 for the owner to test.
Have not asked how it worked out or if he as enlarged it or shot the rifle much.
Dan
He who dares not offend cannot be honest. Thomas Paine

mtech

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Re: Touch Hole I.D./Touch Hole Liner I.D.
« Reply #15 on: March 16, 2013, 10:25:04 AM »
Straight holes less than 3/32 are less reliable if there is much barrel wall. 3/32 was what was mostly used in the 1960s it would seem. But these are so large that its impossible to keep the charge in the barrel  and will self-prime if the vent is not blocked by the pan cover.

Vents with large external cones tend to flash when dirty so they need to be cleaned. They also are harder to cover with the pan cover
The flat faced, internal cone is the most reliable in the field. Its what the English settled on it would seem and they did the serious legwork in FLs and patented a lot of stuff, most of which was simply "stuff" but some, the Nock breech and the recessed breech by Manton had validity and perhaps some others did as well.
When it get cold, when it gets windy etc etc this is when the touch hole gets tested.
I tend to follow the lead of the English. Find a good Manton shotgun and look at the locks and vents. These are still state of the art. But remember that some were set up to self-prime.
The English spent a lot of time on speed, reliability and consistency since wing shooting was a big sport and poor performance would make this very difficult.
We have to remember one thing. The main charge is ignited by RADIANT HEAT. There is no flash of fire into the vent for any distance since the bore is SEALED when loaded and it would take considerable pressure to do this. The primer flash is very low pressure since the pan is open to the atmosphere. So the more heat the main charge "sees" through the vent. The closer the charge is to the pan the more heat it sees. Larger vents work the same way. But a vent like this

Is pretty hard to fault.
I tend to build my own liners similar to WL
Dan
Do you have any of those liners for sale in 5/16 X 28? What's the diameter of the hole in the above liner?