Priming powder location in the pan

[paulvallandigham]

I am shooting two flintlocks right now. One has the vent situated so that a line across the top of the pan splits the vent hole in half, half above and half below the line.

The other has the vent hole located above the pan. In this second gun, I load the pan full of powder, level with the top, and I get very quick ignition.

With the other gun, I load only about 1/3 the capacity of the pan, and bank the powder away from the barrel and touch hole. I get equally quick ignition. If i were to fill the pan with powder, so that the powder was right under, or even covering up half the vent hole, ignition is slowed notciably.

Air is rushing into the bottom of the burning powder, and the hot part of the flames is above that surface. When you load the pan right up to the vent, or block it, the cool air prevents the heat above from getting down and into the vent to ignite the main charge. The powder has to burn DOWN to a point where the rising heat can enter the vent hole to ignite your main charge.

The gunmaker-- Craig Witte, of Farimount, Illinois-- understood this about Flintlocks, as his Father( O.E." Curly " Witte ) is a gunsmith and gun builder, and Craig has been making and shooting Flintlocks since he was a kid, learning at his father's shop. He set the hole in my fowler higher so that the pan can be filled. Then he widened the pan and polished the heck out of it to make it a larger target for sparks to hit, and to make it much easier to wipe clean after each shot with a cleaning patch.

I have fired Flintlocks owned by other men with the vent hole down towards the bottom of the pan. Unless the flashpowder remained banked against that outside wall of the pan, you suffered the " fuse effect " delay in ignition. If you are shooting off a rest, that may not be much of a problem. Shooting off-hand, it is.

 

[Claude Mathis]

I would read the cards as the opposite conclusion. The explosion nearest the touchhole, for example, is most concentrated and expands as it travels outward(away) and upward. That outward bound focused explosion energy doesn't necessarily fire a spark into the touchhole which is a tunnel leading in the opposite direction.

I tend to agree. Igniting powder up against something will definity discolor it. The discoloration on the paper doesn't tell us anything about what's going through the touchhole. IMHO

 

[rabjr]

I tried all three spots when working with my Smoothie this past summer. It with it's big Chambers lock really seemed to prefer the powder dead center in the pan.

 

[Vaino]

An interesting experiment would be to insert a thermocouple into a TH of a fake bbl from the backside and measure the heat when the thermocouple tip is back a 1/32" and progressively moving it back until 1/4" is reached. The 1/32" would simulate a TH liner and the other distances would simulate a plain, drilled TH. The radiant heat generated from different primer locations in the pan could be compared along w/ the length of the TH land. The thermocouple at 1/32" back could receive the benefit of greater heat and also greater odds of a random redhot powder granule, whereas the thermocouple 1/4" back would most likely only see radiant heat......Fred

 

[rabjr]

What about mounting a barrel or a piece of a barrel, with the breech plug removed and capturing whats going on inside at the moment of ignition with the camera?

 

[Deadeye]

Also it doesn't tell us anything about how long it took for the fire to burn up to the paper. It may have taken twice as long for the one against the paper as for the one farther away. Time is of the essence for flinters rather than the size of the explosion.

 

[Flint62Smoothie]

I'd like to see this done with a thermal paper that could only capture a 'hit' if the spark/flame was above a certain temperature.

Thanks Pletch, this was cool!

 

[Dphar]

Since the touchhole is not open, it is plugged by the powder and ball, it would take a relatively high pressure gas wave to enter very far. I think it has to either be radiant heat or some hot partical has to enter the vent.
Any testing would not be representative if the vent was open on the back to allow photography because it would allow pass through of the hot gases.
I suspect its radiant heat that does it. But my liners or the White Lightning put the main charge so close the the pan that any of the three might work in this case. Main charge is never more than .040-.050 from the pan.

I know that an open vent with a counter bore on the outside that has much fouling buildup in the counter bore will often produce a flash in the pan. This leads me the think that this fouling either insulates the vent somehow and the radiant heat does not reach the main charge as well or it interferes with the sparks entering.
?
In simple drilled vents, 3/32" or so I am sure is has to be radiant. Since the hole much longer. Unless there is powder in the vent it would be difficult for hot gases to compress the air in the vent enough to penetrate that far and though I suppose the fireball might throw burning powder grains in? But this is really all opinion and food for thought.
It just seems to me the radiant heat would get there before particles.

Dan

 

[roundball]

The discoloration on the paper doesn't tell us anything about what's going through the touchhole.

Actually, that would apply to all three positions where priming was located.



I've always banked mine away since I started with Flintlocks but this is an interesting experiment, some good dialogue...so I'll ask this:

Clearly the closest location gave the most intense 'signature' against the paper...so why WOULDN'T it also follow that the most intense heat pulse would be felt there as well?

I understand the point that the OUTSIDE edge of the flash would be expanding away from the vent but so what...the outside edge would always be expanding away from the the vent no matter where it was positioned.

The inside edge would be expanding directly into the vent from the git-go.

 

[Dphar]

Go read up on explosive theory, especially shaped charges: shaped charge mechanics is what we are talking about here. You need not go deeply , a shorter explanation will do as from wiki. My own theory, not fanatical belief, is that steel shavings(sparks) come off that frizzen, and are hot enough to ignite what I have determined by observation to be my best pan charge for ignition for this gun. That charge of crushdown, has NO GLAZING(graphite coating), as I have crushed it (I only have used DuPont or Goex), and the fineness is from less than the fffg I started with to near talcum powder-like. With the charge biased in position from the outside of the pan toward the bottom of the pan under the flashhole, the sparks hit it like the electrically fired sequential charges in a strip mine to some extent, and the pan explosion travels from the outer pan to the inner, the length of the pan , or wherever it lights off, blasting fines, chunks, and various burning, burnt, and unburnt particles toward the touch hole, BECAUSE OF THE SHAPE OF THE PAN, AND A BIT OF RESTRICTION FROM THE FLINT, LOWER COCK JAW, AND FRIZZEN BOTTOM, direct the flash to the touchhole like a shaped explosive charge in a weapon is directed. Particles and heat energy penetrate the flash tunnel, long or short and the gun charge lights off. PHEW!!! Not as neat as a cap for sure, and every dang gun different too, in ignition requirements, except for aged wisdom: tip that pan powder outward before pulling the trigger. That's my theory and I reserve the right to change my mind anytime I think better. Wonky

While the pan cover and the flint in the cocks jaws surely help contain the fire closer to the vent it is not going to work like a shaped charge which requires very close tolerances and specific criteria to work.
Compared to the detonation speed of the HE used in shaped charges the burn rate of BP is pitifully slow.

Dan

 

[Larry Pletcher]

This topic has brought on more thought provoking comments that I would have guessed. I wish I had the resources to try all the suggestions that have been made. However, as Paul Harvey says there is a “rest of the story”. For that last 20 years I have been at this type of stuff on an “on and off” basis. Because of the science involved, I try to not let my opinions color what I do. I hope you can understand how hard this is. I shot flintlocks for nearly 30 years and have owned some that were very poorly made and some really good ones. I timed a lock for the first time in 1988.

For most of this time Bill Knight has been an advisor and mentor. He is IMHO the most knowledgeable person we have when BP is mentioned. When I started this project I wrote to him and laid out my current opinions and where I wanted the experimentation to go. In part this was my position about BP igniting in air.

"If we could suspend an amount of prime in the air with no support and ignite it, the burning gases would travel in all directions equally at a predictable rate. The combustion shape would be a sphere. If we place this BP on a flat plate and repeat the ignition, the gases would travel in all directions permitted by the plate, and we would have a hemispherical combustion shape. I believe that the rate of speed at which the gases travel would be the same in all directions. If we place the prime in the pan of a lock and ignite it, the gases travel in every direction permitted by the container just as it did above. This time the pan shape and the barrel wall, frizzen and cock all limit the travel by being in the way. But part of the burning gases, headed toward the barrel wall, travel through the vent. If the vent is clear of crud, the gases should travel through the vent at the same speed as burning gases traveling in other directions. The length of the vent into the powder and the size, shape would all have some effect."

Bill’s response was to suggest a few experiments to clarify some of this. He suggested igniting some BP on a sheet of paper and to note the way the ignition traveled. He suggested I ignite the BP in the center and at the edges. Here are Bill’s instructions:

“On a piece of white paper place a pile of powder. Ignite
the center of the pile with a heated wire. The initial
ignition of a grain, or a few grains, blows the other grains
out in a circular pattern, roughly 360 degrees in shape.
You see trails on the paper left by grains burning while
moving just above the surface of the paper.
Then in 4 trials, light piles of powder from the four point
of the compass. You will note that the majority of the grains
are blown away from the point of ignition in a fan pattern.”

I ignited 20 gr of Swiss on sheets of paper in the center of the pile, on the right and left edges. I first tried fffg and then repeated with ffffg and ffg, all Swiss. I saw the same patterns that Bill described. The fan pattern away from the ignition point showed in all grain sized. Larger grains “painted” with broader strokes, but all sizes showed this.

Here are photos of the patterns. First ffffg Swiss ignited in the center, right, and left edges:

(Ignited in center)

(Ignited on Right)

(Ignited on Left)




Here are ffg Swiss ignited in the center, right, and left edges:

(Ignited in center)

(Ignited on Right)

(Ignited on Left)


Swiss fffg show the same patterns, so I did not include them here.

-----------------------

OK, so what did I learn? I have to be careful here. I suspect that we can make some general statements:

In air BP burns in all direction the same way; unless something gets in the way ”“ like a pan, barrel, frizzen, flint, etc.

In air BP burns away from the ignition point; if the ignition point isn’t in the center of the BP, it burn strongest in the direction across from the ignition point. (Perhaps in the direction of the longest expanse of powder remaining.)

From here on the provable science gets hazy, at least with my limited equipment. (Remember, I’m trying to avoid making a claim I can’t back up.) Here’s food for thought, though. In a pan, if the igniting spark landed in the center of the prime, one would expect the gases to travel both directions equally. But what happens when a bunch of sparks land? Multiple sparks are great, but they make speculating about exactly what happens impossible.

If I prime the pan with the powder close to the vent, the sparks will likely land on the opposite side from the vent. Will that help ignition?

If I prime away from the vent, the sparks will likely land between the vent and the prime. Is that a problem?

My speculation on the above is that a well tuned lock will land sparks throughout the pan, and that right or left side of the prime has little importance.

Further testing??? Sure.

I would like to aim a digital camera straight down the muzzle of my 2” stub barrel and see if we can photograph the differences in: priming methods and high/low vent locations. I have a cleanout screw directly opposite the vent liner. Maybe the camera will work here. I want to repeat the same experiments on my fixture and time these variations to the nearest 10 thousandths seconds ”“ this was the original experiment.

Didn't mean for this to get so long.
Regards,
Pletch

 

[Larry Pletcher]

Also it doesn't tell us anything about how long it took for the fire to burn up to the paper. It may have taken twice as long for the one against the paper as for the one farther away.

Deadeye,
I agree that we don't know about how long it took. It may have taken twice as long as for the one farther away. It also may have taken half as long as the one farther away, after all the distance it had to travel is shorter. When we hook this up to the computer we'll know the time part.
Regards,
Pletch

 

[Leonredbeard]

I'm going to make the case for actual hot gasses getting all the way through the flash hole. When I first started shooting flinters in 1978, I read a magazine article that said I should bore a hole thru the charge from the vent, crushing the granules of charge powder, and then scoop a little 4f from the pan thru the hole, just enough to lay it on the bottom of the channel. Even with the farily poorly made flinters I was working with this speeded my ignition dramatically and made igniton far more reliable. This means that heat, and maybe hot gasses were reaching deep into the chamber, because I had removed the granules of powder from just insid the vent. On my guns without the chambers liner I still do this. And my ignition and speed is still more reliable and faster. I believe that the pressure wave of the fireball in the pan is sufficient to overcome atmospheric pressure in the vent.
And Larry, if you place that camera where it can catch the needle of flame inside a short piece of barrel, I believe it would be large enough to teach us a few things we didn't know. Once yet again, hee, hee.
volatpluvia

 

[mmahlock]

The discoloration on the paper doesn't tell us anything about what's going through the touchhole.

Actually, that would apply to all three positions where priming was located.



I've always banked mine away since I started with Flintlocks but this is an interesting experiment, some good dialogue...so I'll ask this:

Clearly the closest location gave the most intense 'signature' against the paper...so why WOULDN'T it also follow that the most intense heat pulse would be felt there as well?

I understand the point that the OUTSIDE edge of the flash would be expanding away from the vent but so what...the outside edge would always be expanding away from the the vent no matter where it was positioned.

The inside edge would be expanding directly into the vent from the git-go.

I believe the answer to your question is this. If you bank your priming powder against the touch hole when it starts to burn it has to burn through the bank of powder before any heat or fire gets to the touch hole. From my experience having a small amount of priming powder either evenly spread across the pan and not covering the touch hole or banked to the outside end of the pan produces the best results. It is all a mater of timing. If you go to the YouTube site posted above and then look around for a video of a guy with a flint pistol, you will see what happens when you use a whole pan full of powder. The firing time is so slow one might think they had just had a flash in the pan before the main charge goes off. There is also an episode of a gun show that has been on OLN or some such network where a "world renowned" gun expert explains that you can't hit a barn door with a flint lock and he does the same thing, fills the pan so full the frizzen won't close completely and then as he pulls the trigger he turns his head away. The delay between flash and bang was unbelievably long. Again the fire in the pan has to burn its way through the powder before it can get at the touch hole. :surrender:

 

[Sherlock]

It might be possible to do the initial page 1 experiment with a something solid being used instead of the paper, to simulate a fhashhole plugged barrel,not worrying just yet about ignition through the flashhole, and setting the camera to look directly at the working face of the frizzen from 10(?) feet away. When that pan goes off, the camera will capture the SHAPE of the flash. To me there are two parts of successfully blasting that PRB out the muzzle,pan ignition first and then barrel charge ignition. If analysis of the first via camera indicates pan powder placement influences the direction of the pan flash, a major step is clearly in evidence. Would beat the heck out of my dark garage experiments. Wonky

 

[Larry Pletcher]

. . . . . . And Larry, if you place that camera where it can catch the needle of flame inside a short piece of barrel, I believe it would be large enough to teach us a few things we didn't know. Once yet again, hee, hee.
volatpluvia

I wish I had confidence that I could make that work. I'm afraid that my digital isn't good enough. We'll see. I don't know how close I can focus when it comes to seeing into the cleanout or the muzzle. I reckon if I can I'll need to show everybody. This weekend is going to be way too cold to experiment in my shop, and I'll be setting off too much powder to do this in the basement. (I need a bigger R&D budget.)

Regards,
Pletch

 

[roundball]

The discoloration on the paper doesn't tell us anything about what's going through the touchhole.

Actually, that would apply to all three positions where priming was located.



I've always banked mine away since I started with Flintlocks but this is an interesting experiment, some good dialogue...so I'll ask this:

Clearly the closest location gave the most intense 'signature' against the paper...so why WOULDN'T it also follow that the most intense heat pulse would be felt there as well?

I understand the point that the OUTSIDE edge of the flash would be expanding away from the vent but so what...the outside edge would always be expanding away from the the vent no matter where it was positioned.

The inside edge would be expanding directly into the vent from the git-go.

I believe the answer to your question is this. If you bank your priming powder against the touch hole when it starts to burn it has to burn through the bank of powder before any heat or fire gets to the touch hole.

Nobody is/was talking about "banking powder against the touch hole"...it's common knowledge that's a no-no...the tests were left side of pan, middle of pan, and right side of pan. :wink:

 

[Larry Pletcher]

It might be possible to do the initial page 1 experiment with a something solid being used instead of the paper, to simulate a fhashhole plugged barrel,not worrying just yet about ignition through the flashhole, and setting the camera to look directly at the working face of the frizzen from 10(?) feet away. When that pan goes off, the camera will capture the SHAPE of the flash. .. . . . Wonky

Your suggestion may work, but my experience with photography makes me think that the flash shape will be obscured by smoke. However I try a lot of stuff that doesn't come out like I thought it would. If it's too cold to work in my shop this weekend maybe I can give it a try.

If the phohography angles don't pan out, I'm not too worried. The timing program will tell which priming technique is best. I agree that a pic that defines the best priming method would be cool, but I couldn't be that lucky.

Regards,
Pletch

 

[Sherlock]

Pletch, I fired a gun many times with a normal priming pan charge only to observe just what I suggested in an attempt long ago to figure this thing out. Dark garage, night blindness every shot, smoky garage, wait, wait, etc. Speed of light is quicker than speed of smoke, but you can't tell that as in standing behind a flintshooter in the daytime, with respect to pan flash, because the jet out of the flashhole blows straight out of the hole well past the smoke from the pan so quickly I never could separate pan flash and barrel charge jet that I saw in the day time as one event. At night in my garage I got a retina image, as from a flash bulb effect that caused night blindness from the pan charge only, suggesting by shape that powder was better on the outside to throw whatever into the flashhole. That is why I suggested a two part look at the process starting by looking at the frizzen face to confirm photographically what appeared to light off the pan in favor of better through the flashhole ignition as a start point. Wonky

 

[Old Salt]

I want to address the question of whether a spark or heat ignites the main charge.

I recently built a flintlock kit that uses a CVA barrel and breech. The kit came with the touch hole liner installed in the CVA drum?? if that is the right term, the threaded bolt that forms part of a CVA breech. It's a flintlock.

Not knowing the drum was turned 180 degree backwards I took the rifle to the range for the intitial test run. Loaded normally the first shot was a hang fire. In hindsight I figure the threads of the drum(??) were clean enough to allow heat/hot gases to pass the threads and ignite the main charge.

After the first shot the only way I could get ignition was to fill the vent area with 4F prime. Four more shots were hang fires. I'd guess the extra powder in the vent area produced enough hot gas/flame to pass the threads into the main charge.

After disassembly in the shop I was surprised to learn the drum??/vent assembly was 180 degrees out of alignment with the main charge. Which also explained to me why I could never feel powder behind the vent when loading normally.

After correct asssembly the rifle shoots great.

But, following the original vein of this thread, I am 100% confident that hot gas/flame is the main cause of flintlock ignition. A spark or burning piece of powder might get through the vent from time to time but I'd put my money on hot gas most of the time.

I was always taught to load the prime away from the vent. So I do, but I know that all rifles aren't created equal so it's doesn't hurt to experiment.

Old Salt