touchhole liner size

[gungho]

I have searched on here and cannot find the size to drill out the touch hole on a flint lock I drilled out mine with information from this forum and it works perfect I should have writen it down now my friend just bought a lyman flinter and wants me to do the same as mine so thet the ignition is as fast as mine but must be getting old and can't remember the size I drilled it to my search skills leave some thing to be desired
any help would be appreciated
Gung

 

[roundball]

A hole size an eyelash under 5/64" (.070") is what all my liners come with...#50 drill bit

 

[mazo kid]

Try different size drill bits in your vent liner until you find the one that just fits, then drill your friend's liner. I bought a rifle from a friend who had drilled the liner out so that the rifle will (most times) self-prime. There are those who will say that is too large, will lose velocity, etc., which may be true. However, the rifle has near instantaneous ignition and has taken several white tails. I MAY change it out soon just to see if the ignition stays the same.

 

[Many Klatch]

I start off with a #52 drill bit. If that doesn't work I go to a 1/16th. The touch hole isn't too big until the ball rolls out.

Many Klatch

 

[roundball]

The touch hole isn't too big until the ball rolls out.

:grin:

 

[cowpoke1955]

On my GPR I was having some ignition problems. I drilled the touch hole to 1/16th" and that helped some. I redrilled it to 5/64th" and coned it inside and out. That seemed to solve 99.9% of the problem :thumbsup: .

 

[Larry Pletcher]

There are a number of bits between 1/16 and 5/64th:

1/16"--0.0625
50---0.064
51---0.067
50---0.070
49---0.073
48---0.076
5/64"--0.078

I'd work my way up until I was pleased with the ignition. If you need a hole bigger than #49 I bet there is a bigger problem. Personally I like a #51 or #50. If these don't work for me I look at fouling as the problem. I also like using a pipe cleaner to clean the hole. I have found fouling in the hole after using a pick, but I've told that story before. :grin:

Regards,
Pletch

 

[rancher]

The touch hole on my GPR is drilled out to 5/64"

 

[renoman]

The touch hole on my GPR is drilled out to 5/64"

Me too.Tried 1/16th first,much better with 5/64.

 

[Bill Bryan]

If you are using 3F black powder then a 1/16" drill is about right. If you drill it any larger the powder almost self primes the pan. I'm not a fan of that.

 

[jtmattison]

The touch hole on my GPR is drilled out to 5/64"

Me too.Tried 1/16th first,much better with 5/64.

Same here. I cone mine with a larger bit also.

:thumbsup:

HD

 

[Zonie]

Generally speaking, IMO the larger bore guns are less affected by large vent diameters than the small bore guns.

Put another way, using a .078 diameter vent on a .32 caliber rifle or pistol will reduce the velocity of the ball more than it would in a .54 caliber gun.

This makes sense as the larger caliber guns use much larger powder loads so they can afford to use larger diameter vents without loosing as much of the working energy of the load out thru the vent hole.
Of course the gas loss caused by using a large vent in a .32 or a .36 can be made up for by simply adding more powder to the main charge but when all is said and done, I lean towards using the smallest vent diameter that produces a reliable fast ignition. Nothing larger and nothing smaller.
The way to find out just how large the vent needs to be is to start small and increase the size in steps until the number of mis-fires drops to your level of expectations.

 

[ohio ramrod]

A few years back they had an atricle in mussle blasts where they ran several tests and found that a 1/16 coned vent hole gave the fastest time with the most consistant velocity. But coning the vent liner is really fine machining to get the cone right .

 

[Larry Pletcher]

A few years back they had an atricle in mussle blasts where they ran several tests and found that a 1/16 coned vent hole gave the fastest time with the most consistant velocity. But coning the vent liner is really fine machining to get the cone right .

I wrote the article you mentioned; it was in the Feb 2000 issue. The test used straight cylinter holes of varying sizes. The 1/16" hole was slightly coned on the exterior. (No coning was used in the interior.) Actually the 1/16" hole was timed before and after the coning. Coning cut more than .003 sec. off the time.

I have since timed liners that were faster than the times gathered in this article. Liners are faster than straight cylinder holes.

Regards,
Pletch

 

[gungho]

what liners did you find to be the fastest I was thinking of getting a rmc liner
gung

 

[rabjr]

I drill out the Chambers White Lightning liner to 1/16 when I install or have them installed and they work fine for me. :thumbsup:

 

[Larry Pletcher]

what liners did you find to be the fastest I was thinking of getting a rmc liner
gung

Chambers White lightning is the only liner I tested. I should have been more clear. I timed vent locations using the Chambers liner. I was trying to find out whether a ligh or low hole location was important. In those tests the Chambers liner averaged .037 - .038 as opposed to the .0406 that I got with the straight cylinder hole (1/16 w cone). I attribute the difference to the barrel charge being closer to the pan. If that is true other liners may do as well. I have no numbers to back that statement up tho.

Regards,
Pletch