Coning flash hole liner

[Daryl Pelfrey]

Has anyone cones the outside of the flash hole liner where it faces the Pan? If so did it help speed up ignition.

[wattlebuster]

All my liners are Chambers white lightning. They are coned on the inside. No need to cone the outside

[Hungry Horse]

Way back when touch hole liners were pretty much a s.s. set screw with a hole in it, I coned a touch hole liner from the outside. Since I only did one, and really didn’t know what I was doing, you can take it for what it’s worth. I found little or no improvement over no coming at all. I don’t know why it didn’t seem to vastly improve the ignition, but it didn’t. A short time later somebody did a how to, in the Buckskin Report, on how to make a liner with an internal cone. I bought a stick of 1/4-28 s.s. allthread and went into production.

 Hungry Horse

[Daryl]

Has anyone cones the outside of the flash hole liner where it faces the Pan? If so did it help speed up ignition.

I suggest:

1/.-remove the cheap liner
2/.-go to Jim chambers site and purchase the correct size liner with proper drill (to clean up the 1/4x28 hole) and tap
3/.- install Chambers liner

[EC121]

I have occasionally coned the outside.  Usually when I find a flash channel that is longer than I like.  It seems to help some, but I do it only after drilling the hole to the proper size and checking the length of the channel.  No idea how much it helps, but I feel better about it.    If I can't see powder almost right up against flat, it is too long.  I just turn a bit by hand to countersink the outside.

[Turtle]

 I install white lightnings so that when bottomed they are proud of the barrel. Then I file them down flush with the barrel. This shortens the small hole going to the coned area.  I think a shorter distance to the cone helps ignition-can't prove it though. This hasn't shortened the life of the liners I have installed.

[Joe S]

According to Larry Pletcher's testing, neither internal nor external cones have a meaningful impact on ignition speed.

[D. Taylor Sapergia]

The only externally coned vent I have ever seen was on a fowling gun by ... shoot, the name escapes me!  There was no liner - just a cone drilled into the side of the barrel.  Ignition was very poor.  So I installed a Chambers' liner and everything charged.  From lousy to almost instantaneous.  The beauty of the Chambers style liner is that the main charge is brought right out to the edge of the pan...you can see the charge in the vent.  The other style simply made a funnel for the pan flash, and it did nothing to shorten ignition over a simple drilled vent.

[hanshi]

I've never used a White Lightning liner but all the liners in my guns are ss, including the spares I seem to have had around forever.  Any new liner I acquire, whether in a gun or just an extra, has two things done to it.  First I drill out the vent to 1/16".  Secondly, I enlarge the inside cone with a Dremel tool.  Maybe it helps and maybe it doesn't, but I get great ignition, though.

[OldMtnMan]

According to Larry Pletcher's testing, neither internal nor external cones have a meaningful impact on ignition speed.

If that was true then the White Lightning wouldn't work, but there are too many satisfied customers to say that.

[Pukka Bundook]

Same here Hanshi,
I make my liners out of 3/8" stainless, and well coned out on the inside. (with a drill then at least  a 1/16" touchhole sometimes a 5/64".    A 'normal' liner near fits inside these, and ignition is very good.

[Larry Pletcher]

According to Larry Pletcher's testing, neither internal nor external cones have a meaningful impact on ignition speed.

If that was true then the White Lightning wouldn't work, but there are too many satisfied customers to say that.

I respectfully submit that I may have been misinterpreted. The "meaningful impact" is meaningful to me.  I use Chambers liners. I also like a counter sink spun by hand on the exterior of the vent - mainly to take away any burr left from drilling.

I have a flint gun vent made with an interior coning tool with a cutter meant to duplicate a Chambers cavity.  Tom Snyder, at the same time, included a "round-over bit" to make a gentle exterior opening. "Round-over bit" is my term and not Tom's, but it makes a very smooth, gentle vent opening.  I have not timed it, but feel it works very well. 

I don't like long vent holes and think the closer the pan powder and the charge are, the faster the ignition. I like to see the barrel charge peaking through the vent and the pan powder against the barrel flat as close as possible to the main charge. My opinion is that two charges that close together ignite as one charge.

The last work I did on vents is in the link below:
https://www.blackpowdermag.com/part-6-high-and-low-vent-experiments/
I spent more time on location of pan powder than on length of vent , but you get the idea.
Regards,
Pletch

[OldMtnMan]

Very good Larry.

Thanks.

[Joe S]

From Pletcher's data:

White Lightening vs Straight Hole



The mean White Lightening liner ignition speed was faster than a straight hole, but only by 0.008 seconds. These means are not statistically significant (one-tailed Student’s T-test, p =  0.10161), which means that if you were to repeat this experiment, you may find that the average straight hole was faster than the White Lightening.

I stand corrected. "Meaningful" is an opinion. The correct phrasing is that there is no statistically significant difference between straight hole and the White Lightening.

[alacran]

I have used Tom Snyder's coning tool on the last three flintlocks and like Larry I Think it works well. I used a tiny round diamond burr turned by hand to make a slight countersink.

[hanshi]

As I mentioned previously, I really don't know whether interior coning is better than a straight hole or exterior coning; I've never tested to find this out.  But I'm convinced that the closer to the main charge is the prime, the better is the ignition.

[Larry Pletcher]

Jose,
I looked up in my records found the averages of 20 trials were the same as you mentioned.  My standard deviations are not the same as yours.  I won't claim to be a whiz in statistics, so I don't plan on defending the numbers in my articles. I do have faith in them.

Kind regards,
Pletch

[Joe S]

Hanshi:   From Pletcher's data, there is no statistically significant difference between an external cone and a straight hole:



(For two-tailed T, P = 0.7541).

[Joe S]

Larry - I don't know why our standard deviations are different. What did you find?

Maybe this evening I'll take a look and see why we got different numbers. Part of it may be that for the white lightening you had a total of 60 trials from all of your combined tests. The combined value is what I used. If you are looking at a standard deviation from just one set of 20, I would expect there to be some difference.

I also have faith in your numbers Larry. Your experiments are well designed and executed. By taking topics out of the realm of subjective observation, and making actual scientific measurements, you have made a huge contribution to the study of black powder guns.

[Daryl]

What was the length (wall thickness) of that straight hole.

Was it a 1/10" (some commercial guns) thickness of barrel at breech with a straight hole compare to a coned liner on the same thickness.

How does a 1/10" vent hole thickness/depth/length compare to  2/10" thickness hole/depth/length, or 1/4" thickness or depth of hole - all compared to a WL liner in each?

I think this sort of testing would hold more validity than saying A drilled hole vs. A WL liner - have "X" times - seems closer to "Y" times to me.

[Joe S]

You'd have to check with Larry on that. In his tests, he used the same barrel, so the results are comparable, but what the actual wall thickness was, I do not know.

[Daryl]

Seems to me that would be quite important.

[Darkhorse]

My first flintlock was a GPR and ignition was terrible. I never knew when it would go off, mostly it didn't. I looked closely at the metric liner and decided it was the culprit because of poor design the prime fire couldn't get to the charge. Now realize at this time I had never heard of a White Lightning liner so I just modified the lyman liner as I thought it should be.
It had a deep screw slot across the face and I used a ball endmill to cut a path through the slot and put a small chamfer in the touch hole. The results were like night and day. All of a sudden I had a rifle that would actually shoot when I pulled the trigger. I don't know if the outside chamfer helped any or not but the rifle went off so fast I included it on any liners I modified. And I modified quite a lot as most guys I knew with factory rifles had the same problem.
When I install a White Lightning I put a slight chamfer on the face with a hand held counter sink.
This is the drawing I made about 30 years ago when I was working out my modifications.

[Daryl]

With my WL liners in my 3 flinters, after loading I can look at the vent and see a powder granule through the opening.

[Larry Pletcher]

What was the length (wall thickness) of that straight hole.
Was it a 1/10" (some commercial guns) thickness of barrel at breech with a straight hole compare to a coned liner on the same thickness.
How does a 1/10" vent hole thickness/depth/length compare to  2/10" thickness hole/depth/length, or 1/4" thickness or depth of hole - all compared to a WL liner in each?
I think this sort of testing would hold more validity than saying A drilled hole vs. A WL liner - have "X" times - seems closer to "Y" times to me.

Daryl,
I feel as you do that wall thickness with a straight hole vent is important. I have a project in mind to see if I can find answers.  One idea is to use a barrel stub with a straight 1/16 vent.  The barrel wall at this point is perhaps irrelevant.  I would time the vent ignition.

Then I'd have .010" milled off the vent flat and retime.  Mill another .010" and time again. This timing and milling could be done a number of times to see if ignition times improve. My gut says that an improvement should eventually be seen, but I don't have data at this time.

 I don't know of a way to make the vent shorter in length other than the milling.  Because a lock plate is bolted to the flat, I think the whole flat would need to removed. Ideas?
----
Another test that I did not get done was with the web on a Tom Snyder milled vent. ON my gun I intended to cut the interior cavity in steps to leave a .040" vent web and time ignition.  Then unbreech and cut the cavity deeper, stopping with a .020" web and retime. I did not get this done.  The gun now has a .020" web, and I don't intent to cut the cavity closer to the surface than that.

There may be chances to get the straight vent/milling test done later.
Regards,
Pletch