2 winters ago i was asked to build a flint lock for a customer in texas. i did. im close to the fur trader museum out side of chadron ne. it was fall and the museum was still open when i started the build. what size vent hole should i use? when i went to the museum to look at the hundreds of flintlocks they have with a flashlight to look at the vent holes this is what i found. ever size you could think of from very small to very large. i dont remember what size i settled on but it was a tiny bit bigger than average. the gun fired well and my customer got his deer right off with it. WHAT IS THE PERFECT SIZE FOR A VENT HOLE AS I MAY WANT ONE OF THESE ROCK LOCKS FOR MY SELF SOON? some of the trade rifles i saw had really big flash holes. they must of wanted it to go off no matter what and dont stand beside it or you would get blistered good. i covet all your expert advice, thanks before hand. some were so small i dont know how they went off.
vent hole size.
- Thread starter Cattman
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Bob McBride
54 Cal.
I’d say 1/16”. Others say different. I’d also surmise the vent holes you saw were mostly burned out to different diameters, with a certain percentage wallowed out as a particular owner preferred.
Phil Coffins
69 Cal.
A vent liner with a .060” hole is what I start them out with. That’s big enough to be fast and small enough to not leak powder. When it gets burnt out a new one can be screwed in.
Pete G
76 Cal.
.0625"
I like .0625”(1/16”) in my rifles.
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Stophel
75 Cal.
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1/16" may be fine with a White Lightning liner where you have a huge cone that comes almost to the outside surface of the barrel, but with a hole drilled in the side of a thick breeched barrel, it just won't do. 5/64" is generally good. I will cone them some on the inside too, but I actually don't notice a difference.
cullen1780
32 Cal.
5/64" gets my vote.
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That works out to be .0781 as opposed to .0625. Quite a difference!
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I believe the views of Ezekiel Baker that a Rifle vent is as well at 1/16th " but a musket should be as he puts it 'One sixteenth & one 32nd Part" in other words 3/32" size vent for a musket . That a vent will shoot larger is true .He made enough Rifles to form his opinion
. Rudyard
. Rudyard
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Wow that is .0937!, quite a hole for gas to blast out of !
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5/64" gets my vote also. I've never had great luck with a 1/16" - especially if it has a liner. Just seems to clog up to quickly. As soon as I opened it up to 5/64" the ignition problems went away.
grey8833
40 Cal.
Nice report on the subject, with data:
https://www.blackpowdermag.com/touch-hole-ignition-timing/
https://www.blackpowdermag.com/touch-hole-ignition-timing/
ohio ramrod
75 Cal.
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If my mind is correct(which it isn't always)A few years back the bevel brothers did some serious testing and concluded that 1/16th gave reliable ignition and the best groups.
In the smaller calibers such as my .40 I find a 1/16 vent hole is very fast and consistent. However I'm first a hunter and as such I want more instant ignition so my vent holes are larger as is the caliber. How large?
Well I drill a 1/16th hole in a white lightning liner and go to the range and shoot it some. If it is not to my likeing I will drill it out one(1) number drill at a time until one gives me the performance I'm looking for. Then I shoot that one for awhile and maybe from now on.
Well I drill a 1/16th hole in a white lightning liner and go to the range and shoot it some. If it is not to my likeing I will drill it out one(1) number drill at a time until one gives me the performance I'm looking for. Then I shoot that one for awhile and maybe from now on.
Response through a touch hole depends on too many variables to set a standard diameter. Of course diameter of the touch hole is one variable. Another is the thickness of the barrel. Then you have internal cones with the size and shape of the cone. Now we have to integrate the touch hole with the lock. While optimal position of the touch hole is the sunset position, slight variations are tolerable for fast ignition. Then there is the depth of the pan and quantity of powder in the pan. Then the position of the touch hole with respect to the surface of the breech plug. What is the influence of fouling at the breech?
Getting quick ignition from a flintlock is an art, not a science. No standards apply. Its just what works for that particular firearm.
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I made my own liner with A-2 tool steel starting at .059 and an exterior funnel. It was not reliable. I just opened it up to .063 and tapered the hole with a diamond round hone from the out side. It did get better at the next size larger but still is not where I think it should be. It is pretty reliable now but not as fast as I think it can be made to be. I have not tried it again after the work on the vent with the tapered round diamond file.
I've been told that if right they are nearly as fast as percussion and mine is not there yet.
I've been told that if right they are nearly as fast as percussion and mine is not there yet.
You might want to try making another vent liner, this one with the cone on the inside leaving the outside flat the way the White Lightning liner is made.
Although an exterior funnel shape looks like it will direct more of the flash from the pan into the hole in the middle so it is a good idea, that's not necessarily true.
We are talking about the gas from pan flash moving at a very high rate of speed. As such, it is possible for the gas to deflect off of the coned wall towards the center of the liner and converge right at the vent holes mouth. In this location, it can create a high pressure zone that blocks off the gas that was trying to enter the hole in a straight linear fashion from the source of the gas.
In other words, the cone may keep the pan flash from getting thru the vent hole.
There are reasons that things like vent holes on the old original flintlocks don't have exterior cones.
If there weren't reasons, we would see vent holes with cones on the outside of the barrel on thousands of the old original guns. Instead, what we see is the exterior of the barrel left in the same shape as the rest of the barrel in that area. In some of the old guns the builder did go to the trouble of forming a cone on the inside of the barrel that led into the vent hole.
The easiest way to do that without installing a dedicated vent liner, was to drill completely thru the barrel wall opposite the vent hole and then to drill about half way thru the barrel wall where the vent hole was located. After this internal "cone" was done, the hole thru the barrel wall opposite the vent hole was threaded and plugged with a screw.
On other old guns, the builder used a special little machine made with several small gears in a line with each gear driving the next one and the "outer gear" connected to a crank. The gear furthest from the crank was fitted with a small rotary burr cutter which formed the cone from inside the bore.
That's a pretty fancy little machine but with the improved speed of the flintlock gun that had this machining done, the builder appearently thought it was worth the effort.
Although an exterior funnel shape looks like it will direct more of the flash from the pan into the hole in the middle so it is a good idea, that's not necessarily true.
We are talking about the gas from pan flash moving at a very high rate of speed. As such, it is possible for the gas to deflect off of the coned wall towards the center of the liner and converge right at the vent holes mouth. In this location, it can create a high pressure zone that blocks off the gas that was trying to enter the hole in a straight linear fashion from the source of the gas.
In other words, the cone may keep the pan flash from getting thru the vent hole.
There are reasons that things like vent holes on the old original flintlocks don't have exterior cones.
If there weren't reasons, we would see vent holes with cones on the outside of the barrel on thousands of the old original guns. Instead, what we see is the exterior of the barrel left in the same shape as the rest of the barrel in that area. In some of the old guns the builder did go to the trouble of forming a cone on the inside of the barrel that led into the vent hole.
The easiest way to do that without installing a dedicated vent liner, was to drill completely thru the barrel wall opposite the vent hole and then to drill about half way thru the barrel wall where the vent hole was located. After this internal "cone" was done, the hole thru the barrel wall opposite the vent hole was threaded and plugged with a screw.
On other old guns, the builder used a special little machine made with several small gears in a line with each gear driving the next one and the "outer gear" connected to a crank. The gear furthest from the crank was fitted with a small rotary burr cutter which formed the cone from inside the bore.
That's a pretty fancy little machine but with the improved speed of the flintlock gun that had this machining done, the builder appearently thought it was worth the effort.
Many years ago, before I built my own rifles and first used the Chambers White Lightning, I made several hundred of these. If you make your own at least make a couple like this to try out. They give good ignition and are fast also.
