Author Topic: Touch Hole Diameter  (Read 617 times)

Offline Nhgrants

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Touch Hole Diameter
« on: October 13, 2019, 01:49:06 AM »
For a 54 caliber gun that is intended to be used for hunting, would 0.090 inches be reasonable
For touch hole diameter?
Thanks
.

Offline Long Ears

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Re: Touch Hole Diameter
« Reply #1 on: October 13, 2019, 01:53:21 AM »
All I use is a 1/16" or .0625 drill bit. .090 might start a forest fire to your right..... Bob

Offline Dennis Glazener

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Re: Touch Hole Diameter
« Reply #2 on: October 13, 2019, 02:02:49 AM »
For a 54 caliber gun that is intended to be used for hunting, would 0.090 inches be reasonable
For touch hole diameter?
Thanks
.
I also use a 1/16" bit, a .090" would be more like a worn out touch hole! Certainly would be a self primer or close to it.
Dennis
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Offline Frank

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Re: Touch Hole Diameter
« Reply #3 on: October 13, 2019, 02:04:35 AM »
Always start with 1/16 diameter and open it up from there to ensure reliable ignition.

Offline bob in the woods

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Re: Touch Hole Diameter
« Reply #4 on: October 13, 2019, 02:26:28 AM »
A .54 cal barrel can have different thicknesses of wall depending on what type it is . If you are not using a liner, then the increased wall thickness of , let's say a C weight profile or a 1 in straight octagon , will have the powder situated far enough from the lock pan that you may find a 5/64th's hole works better for you than a 1/16th . My own .54 has a 42 in tapered and flared  "C" profile Getz barrel, and I use a 5/64 touch hole ....no liner.   I used it for black bear this Fall, and it is extremely reliable.

Offline heinz

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Re: Touch Hole Diameter
« Reply #5 on: October 13, 2019, 03:18:53 AM »
I always used 3/32. Ignition is very reliable. If you bench test it you will get some vertical stringing, about a 3/4 inch at 50 yards. I am willing to pay that price for hunting and rendezvous ignition reliability
kind regards, heinz

Offline Nhgrants

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Re: Touch Hole Diameter
« Reply #6 on: October 13, 2019, 01:33:18 PM »
Thanks for the replies

Offline okawbow

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Re: Touch Hole Diameter
« Reply #7 on: October 13, 2019, 03:53:01 PM »
My .54 table rifle has a stock size White Lightning liner, obout .045” I think. It goes off every time, and fast. My .54 hunting rifle has a .062” touch hole liner and has never failed to go off the first shot. I use the same gun for woods walks where a hammer fall is counted as a shot, so it must go off every time.

If a .062” touch hole is too small, I would look at another reason for poor ignition. Your gun will be more accurate with the smaller hole, and you can use 3f powder without it blowing out the touch hole when you ram the ball home.
As in life; it’s the journey, not the destination. How you get there matters most.

Offline BJH

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Re: Touch Hole Diameter
« Reply #8 on: October 13, 2019, 04:06:16 PM »
When the time comes, drill and tap for a white lightning liner or similar liner. I normally open the hole to .068 or .070. This is a wire guage drill size. In damp and often humid Pa. I find these diameters to be the most dependable compromise. For a over the log or other target shooting disipline, the stock hole diameter is usually best. BJH
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Offline hanshi

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Re: Touch Hole Diameter
« Reply #9 on: October 14, 2019, 12:16:50 AM »
It's 1/16" for me too.
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Offline Anonymous

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Re: Touch Hole Diameter
« Reply #10 on: October 14, 2019, 04:31:34 AM »
Probably take some flack, but 5/64” (.078”) touch holes have improved ignition times over 1/16” (.060”), pretty much accros the board, in my experience.

Offline L. Akers

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Re: Touch Hole Diameter
« Reply #11 on: October 14, 2019, 03:40:41 PM »
I agree with Okawbow.  If 1/16 is too small, look for other causes.  I believe the primary cause of inconsistent ignition is a flash channel that is too long.  I have been making liners for more than 30 years which look, internally, like Chambers' White Lightening liners and have a flash channel of about .030" and a diameter of .059.  The smaller the touch hole, the more pressure stays in the gun to do work, and the pressure is more consistent which translates to better accuracy.  Non-Chambers liners can/should be modified to emulate the White Lightening liner internally before installation.

Also banking priming powder against (GASP!) the touch hole has been proven by high speed photography to result in more fire inside the breech than banking the priming away from the thouch hole and is NOT any slower.

I get comments about the ignition speed of my guns at shoots I attend and if my priming ignites, the gun says BANG!

Offline Nhgrants

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Re: Touch Hole Diameter
« Reply #12 on: October 15, 2019, 01:27:27 AM »
Where I got the idea for .090 was the book recreating the American long rifle.
It suggested .062 for target and over .090 for hunting.
This book was written over 50 years ago. Would the preference today be smaller
Because powders might be different than there were in the mid 20th century?

Offline Stophel

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Re: Touch Hole Diameter
« Reply #13 on: October 15, 2019, 03:11:04 AM »
I just drill mine now right off at 5/64" (.078125").  They end up getting drilled that size anyway.  I've started drilling smaller holes and trying the gun, and working my way up until I get good ignition (if the hole is too small, I don't get slow ignition, or the so-called "fuze effect", I just get a gun that won't go off all the time).  5/64" pretty much just works.

I have one I drilled at 3/32" (.09375"), and it works very nicely, though many people would tell you that such a big hole will cause you to lose velocity or get bad accuracy, etc....

I also give them a bit of a cone on the inside with the finishing nail coning tool.
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