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Category: Vent Liners

Touch Hole Ignition Timing

Touch Hole Ignition Timing

Reprinted from February 2000 issue of MuzzleBlasts magazine by Larry Pletcher. I was assisted by Fred Stutzenberger who provided the barrel and any needed machining. The tests conducted here are of straight cylinder vents. This article is a work in progress.

In earlier articles on timing flintlocks, I expressed my belief that touch holes caused some of the slow ignition times experienced occasionally by flintlock shooters. In a pair of articles I hope to shed some light on this idea. This article will report on the testing of touch holes of varying diameters. The touch hole shape for this series of tests is a straight cylinder. These tests are planned as a baseline for future testing. A second article will explore the various touch hole liners available to the flintlock shooter. These liners will have a number of configurations, including cones inside and out, as well as different shapes used in making the cone.

The tests done for this article were conducted on a very short smoothbore barrel in which increasingly larger touch holes were drilled. Another barrel was threaded to this section to conduct smoke away and to provide some space between the photo cells used in the timing process. I am indebted to Fred Stutzenberger for his help in providing the barrel and any machining needed to conduct the tests.

I began with a touch hole which both Fred and I considered too small. We used .040 in. as a starting point. Additional diameters were .052, .055, .0625, .070, .078, .082, .094. These holes correspond to drill numbers 55, 54, 1/16, 50, 5/64, 45, and 42, respectively.

Here you see the shield that prevented both photocells from triggering when the pan flashed. (From another test but using the same equipment.)

The barrel was held in place with a lock plate and pan attached to the barrel with screws. One photo cell was placed to “look” into the pan while the second “looked” across the muzzle of the barrel. A shield was dropped into place between them to keep the barrel photo cell from triggering on the pan flash. Both photo cells were connected to a computer by an interface.

The testing process involved loading the barrel with 15 grains of FFFG powder. This amount of powder filled the barrel to a level above the touch hole. This was verified using a cleanout hole on the other side of the barrel opposite the touch hole. The barrel was gently lowered into horizontal position so the powder in the barrel would not fall away from the touch hole. The pan was primed, taking care not to cover the touch hole. The pan was ignited using a propane torch. It was found that the propane torch would not trigger the photo cells and could be directed downward into the pan. Special care was used to separate the torch from the powder used in the tests.

The .040 hole was tested only twice because I felt that it was too small to be practical. Each other hole size was tested 20 times. These tests are located in the spread sheets at the end of the article. After each touchhole was tested, it was drilled out to the next size and testing was continued.

When I got to 1/16 inch, I permitted myself the experimenter’s prerogative of throwing in an extra variable. I have an exterior coned 1/16 inch touch hole in my rifle, so I used a center drill to produce a similar cone on the test barrel. Its results are also included.

The barrel and lock plate are attached to the fixture. (from another test using the same equipment)

During the testing, a number of trends began to develop. It was noticed that with the small touch holes, a number of pan flashes did not ignite the barrel. This decreased as the diameters increased. When .055 in. was reached, this largely disappeared. Touch holes 1/16” and larger had no misfires.

A second result was that the ignition was faster as the hole size increased. The increase was dramatic in the smaller sizes. However, a point of diminishing returns was reached, in my opinion, somewhere above 1/16 in. At some point the improved performance that a larger touch hole seemed to provide was over ridden by the disadvantages of increased vent hole blast and decreases in consistency.

The standard deviation and variation within the tests can be used to demonstrate these trends in performance. Both standard deviation and variation improve as the touch hole size increased to 1/16 in. Above 1/16 inch, elapsed time, standard deviation, and variation are all more erratic.

As I mentioned earlier, the amount of gases escaping from the touch hole increased rapidly. It the larger diameters it was difficult to keep the torch from blowing out. While this was expected, it did serve as a reminder that large touch holes require that the shooter be considerate of the person standing to the lock side of the rifle.

The results of the testing are summarized in the chart below. Complete results of each test are included at the end of this article on the next page.

While cleaning the barrel between tests, I learned something that may be important in firing flintlocks. Looking through the inspection port opposite the touch hole, I saw that the touch hole was partially clogged. A vent pick was pushed into the touch hole while watching from the inspection port. I could see the dirt being dislodged as the vent pick went through. However, as the pick was withdrawn, the dirt was deposited back in the touch hole where it was at the beginning. This was seen more than once. It made me think that running the pick through the touch hole might not do as much good as I once thought.

It might be important to have a big enough touch hole so that even when partially clogged, it still has enough opening to ignite the barrel powder. Another possible solution might be to use a pipe cleaner before loading for the next shot. (In all my flintlock rifles I now use a vent large enough to permit cleaning with a pipe cleaner. – editor)

By the end of my testing, I arrived at two conclusions that will be incorporated in any future rifles I build. One conclusion is that if no liner is used, any touch hole will need to be 1/16 in. or larger in diameter. The other is that it will have an exterior cone. I believe that an exterior cone improved the 1/16 in. touch hole enough to be included. It would, however, be good to test an exterior cone on different touch hole diameters.

As was explained earlier, this article ignored touch hole liners. It was felt that a baseline was necessary for any future comparison. The next article will be devoted to liners. I personally like the idea of having barrel powder lie as close as possible to the pan. I am probably not alone in thinking that liners will show an improvement over cylinder touch holes. However, I am willing to rely on science to demonstrate this. Human senses are not perceptive enough to detect the differences we can measure with the computer.

There are numerous liners and methods of installation that should be examined. I would like to try a sampling of those currently marketed. A liner that seems to function well has been developed by Mark Silver, Robert Harn, and Jim Chambers. It is based upon information from Lynton McKenzie. It will be interesting to compare these liners with the results of this series of tests. As in any scientific study, I hope we will be able to draw some meaningful conclusions.

I do not consider this to be a complete study of cylinder-shaped touch holes. We do have much to learn. However, I have confidence in the results collected and in the methods that Fred and I devised to do the study.

I am open to any suggestions that will further our understanding of flintlocks. Soon I hope to have a web site devoted to flintlocks. In the meantime, please feel free to write me at 4595 E. Woodland Acres, Syracuse, IN 46567 or email me (larry@blackpowdermag.com)

Summary Chart

Larry Pletcher, editor – www.blackpowdermag.com

Because this article was published 19 years ago, I am having trouble locating the photos that were used in the magazine. I added photos of more recent testing that uses the same equipment and methodology. My summary chart is also missing. It appears above, cut and pasted to fit the page. The spreadsheets below are original to the magazine article.

March 10, 2019
Two Hole Vent Test

This test is a long time coming. A couple years ago at CLA, Steve Chapman and I were looking over a flint gun made by Allan Sandy. The vent Allan used had two smaller holes located horizontally. Allan said the vent was internally coned but used two .052″ holes. Allan said he didn’t know whether it was faster or slower than a normal vent. My reply was that I could time it. Allan offered to provide me a vent, and on the way home, Steve and I planned how the vent would be tested.

Time passed with many interruptions in the way. In the meantime Fred Stutzenberger entered the picture. I believe Fred saw the “double-hole vent” on Sandy’s table at the same show that we did. Fred however, was more prompt than we were and published an article on the vent in the August 2014 issue of MuzzleBlasts.

Without great detail, Fred’s article compared Allan’s double-hole vent with a single-hole vent that had the same area as the sum of the two smaller vents. His findings showed that shots fired with the double-hole vent had slightly higher velocities than the single-hole vent even, though the vent area was the same. The “choked-flow principle” (comparing circumference to area) is the likely cause. Fred explains this better than I do; please read the article.

Our testing focused only on ignition speeds. We compared ignition time of the double-hole vent (two .052″ holes) and the single-hole vent (.073″) Both vents have the same area, but vary in their circumferences.

The main question I have is, “If the choked flow principle tends to restrict flow leaving the vent, might it also restrict flow entering the vent, causing slower ignition?”

We used a 10″ barrel stub with a small Siler flint. The test used a double-hole vent with .052 holes and a single-hole vent with a .073 hole. We did 10 trials each and lit the pan with a red hot copper wire. Our reason for this was to prevent a changing flint edge from entering into the test. The single .073 vent was better both in speed and consistency.

Before finishing, we ran 5 trials each in which the pan was ignited by the small Siler. In those trials the single-hole vent was better, but by a smaller margin. None of the trials sounded abnormal to the ear. No matter the range from high to low, human senses could not tell the difference. In fact, Steve tried to guess and was invariably wrong.

Here you see the shield that prevented both photocells from triggering when the pan flashed

Interpreting the results can sometimes be misleading. In this case, I like the single-hole vent. However, I do have two doubts. (1) I have questions about the reliability of a vent as small as .052”. A double-hole vent with larger holes might alter the result. (2) I wonder if the shape of vent’s exterior would change the result.

The included photos show the fixture and the position of the photo cells used in the timing. The photo cell at the pan trigger the start, while the photo cell and the muzzle triggers the stop.

The last pic is a close up of the vent. These holes are .052″. BTW, the stock is a heavily mutilated factory second supplied by Jim Chambers. It was important because it allowed the sear to be struck from below by the plunger. It also allowed us to use a small Siler lock for an earlier test. At that time it allowed three different locks to be tested using the same lock mortice.

To conclude, I’d like to thank Allan Sandy for the chance to time his vent. I feel that this vent type is well worth studying. I’d like to repeat this with a .055” 2 hole vent.

My thanks also to Steve Chapman and Mike Coggeshall for their assistance in the testing.

Of course every experimenter needs a furry assistant

Larry Pletcher, editor

September 21, 2016
Pan Vent Experiments – An Introduction

[box type=”note” align=”aligncenter” ]Learning how black powder ignites in a flintlock has been a passion of mine for 20 years. In this series of tests we examine the way fire travels from the pan to the barrel. The process involves the use of camera, computers, and a physics interface. What we learn may change the way we think about flintlock tradition.[/box]

Introduction

This series of experiments has evolved into one of greater scope than originally intended. Earlier intentions were to examine the ignition qualities when the position of the vent hole varied up or down in relation to the pan. The methods to investigate included a computer timing procedure used to measure times from a barrel stub and lock plate with a pan attached.

An L&R plate was chosen because the pan was attached. The plate was drilled and attached to a barrel stub with screws. The rear screw is attached to the barrel through a vertical slot in the lock plate. This allows for adjusting the height of the vent hole in relation to the plate.

At the rear of the plate a hole was drilled to provide a pivot point so that the barrel could be rotated to vertical for loading. The barrel is two inches long but is breeched by using a plug with an octagon shape, providing the same dimensions as the barrel.

The computer equipment used included a science interface designed for use in high school physics classes. The hardware was designed and built in the late 80’s. The computer is of similar vintage, but the combination allows measuring time intervals to the nearest 10,000th of a second.

This photo shows the fixture holding the barrel and the photo cells positioned at the pan and muzzle.

Pan Ignition Experiments

The experimentation has been broken into phases. The results of each section will be used in successive testing. The plan is to learn enough to control variables for our final experiment, which will be to the measure and evaluate of different vent locations. Each of the following parts is a link to the actual experiment. Methodologies used will be discussed as well as the experiment and the results.

Part 1 — Black Powder Ignition Characteristics

(Powder on sheets) This phase of testing was suggested to me by Mr. Bill Knight. Its purpose is to identify how the ignition travels across blackpowder exposed to the air as in a flint pan.

Part 2 — Initial Pan Experiments

(Card between barrel and pan) The card test was designed to determine the intensity of the flame at the vent. An index card was cut and pinched between the lock plate and the barrel. The pan was primed in three different positions.

Part 3 — Photography through the muzzle

In this phase I wanted to see if there was a visible difference in the amount of fire traveling through the vent. I used a digital camera to photograph the fire coming through the vent as seen from the muzzle. The camera is aimed to look directly into the barrel muzzle.

Part 4 — Priming Powder https://www.blackpowdermag.com/part-4-priming-powder-amount-by-weight/Amount by Weight

In this part we will examine the amount of priming powder used. Weighed amounts of powder will be timed. Plans call for .5 grains, .75 grains, and 1.0 grains of swiss Null B priming powder.

Part 5 — Timing Powder locations in Pan (Is it better to bank the powder away from the vent?)

The technique is to use photo cells to detect pan ignition and start the time. A second photo cell detects fire at the muzzle of the 2 inch barrel and stops the clock.. The methodology for this phase needed careful thought. Informal trials yielded some times that were out of predictable bounds. I suspect they were caused by an unknown variable, perhaps fouling.

Part 6 — Timing Vent locations (high, medium, low)

This final test will explore the ignition speed when the location of the vent hole is varied vertically. The test will start with the vent centered on the top of the pan. Other tests will be conducted with the vent as low in the pan as one could expect to find and with the vent located well above the pan center line.

April 17, 2008
Part 1 — Black Powder Ignition Characteristics

Black powder ignition in a flintlock pan is different than inside the barrel. Here we look at black powder ignition in open air.

(Powder on sheets)

This phase of testing was suggested to me by Mr. Bill Knight. He has been a valued advisor for many years. I poured a measured amount of black powder on a sheet of paper. The powder was ignited by a red hot copper wire in different locations around the pile of powder – center, right, and left. My result was the same as Mr. Knight described. When ignited in the center the burn traveled in all directions equally. In those where the powder was ignited on the edge of the powder, the fire traveled from the ignition point toward the farthest side, away from the starting point. Included here are photos showing this.

Photo 1 — The burn radiates from the center as we would expect.

Photo 2 — Burn marks indicate the strongest direction is to the left, away from the ignition point on the right.

Photo 3 — Burn marks indicate the strongest direction is to the right, away from the ignition point on the left.

The burns marks above extended well past the area where the powder was placed. In the photos where the pile was ignited to the side, the burn marks extended considerably farther than marks left on the center ignition photo. This test was done with fffg (shown here), ffg, and ffffg powder. Each size left similar burn marks. When testing the ffg powder, I laid out all three sheets of paper side by side, thinking that I would then ignite them one at a time. When I ignited the sheet with the right side ignition, the fire moving to the left was strong enough to jump to the next sheet.

This test caused me to reconsider the long-held advice to place priming powder at the opposite end from the vent hole. This thought has been around for much longer than I have been involved in black powder. My concern is that if powder is near the outer edge of the pan, it is likely that sparks will land inboard of the powder. The experiment we just did caused me to think that the strongest part of the flame would be from the sparks across the powder- the opposite direction we want. What we desire is for the strongest flame to be at the vent end of the pan.

Pan Vent Experiments — Introduction

Part 2 — Initial Pan Experiments

Part 3 — Photography Through the Muzzle

Part 4 — Priming Powder Amount by Weight

Part 5 — Timing Powder locations in Pan

Part 6 — High and Low Vent Experiments

April 14, 2008
Part 2 — Initial Pan Experiments

Burn marks on a card help us to determine the intensity of the black powder burn in the flintlock pan. This was a preliminary step to help determine how to prime the pan.

The card test was designed to determine the intensity of the flame at the vent. An index card was cut and pinched between the lock plate and the barrel. The pan was primed in three different positions. The first was banked away from the vent as tradition suggests. The second was to place the powder in the center of the pan. In last position, the powder was placed as close to the vent as possible without touching. The powder was ignited as in the first test.

Photo 1 shows the fixture, barrel, and the index card in place for the first test.

Photo 2 shows the burn marks left on the index card with the priming powder banked to the outer edge of the pan.

Photo 3 shows the burn marks left on the index card with the priming powder placed in the center of the pan.

Photo 4 shows the burn marks left on the index card with the priming powder placed in the pan as close to the vent as possible without covering the vent.

From the first two experiments I am beginning to conclude that is might be best to prime closer to the vent. The next test was designed to gather more information about this possibility.

Pan Vent Experiments — Introduction

Part 1 — Black Powder Ignition Characteristics

Part 3 — Photography through the muzzle

Part 4 — Priming Powder Amount by Weight

Part 5 — Timing Powder locations in Pan

Part 6 — High and Low Vent Experiments

April 11, 2008
Part 3 — Photography through the Muzzle

Comparing the strength of the black powder burn by looking through the barrel muzzle. Here we see that where the black powder is placed in a flintlock pan is crucial.

In this phase I used a digital camera to photograph the fire coming through the vent. The barrel is mounted on a fixture and the camera installed on the tripod. Height was adjusted until the camera looked directly into the muzzle. In this position the barrel in centered in the camera and the pan is to the left. On the right side of the barrel directly opposite the vent is a cleanout hole. (The cleanout is important as you view the photos.)

The pan was primed with .5 grain of Swiss Null B priming powder in three pan positions: banked to the outside, close to the vent, and as close as possible without blocking the vent. The pan powder was carefully positioned using a pencil with a round eraser. Since the eraser was the same shape as the pan bottom, this worked very well.

The camera was set to have the shutter open for 4 seconds. Once the pan was primed, the procedure was to fire the camera and then ignite the pan. The pan was ignited as earlier with a red hot copper wire. (There is NO barrel powder used until the last phase.)

Photo 1 shows the muzzle shot taken with .5 gr of Swiss Null B priming powder banked away from the vent.

Photo 2 shows the muzzle shot taken with .5 gr of Swiss Null B priming powder positioned close to the vent.

Photo 3 shows the muzzle shot taken with .5 gr of Swiss Null B priming powder positioned as close to the vent as possible without covering it.

Examination of the photos add evidence for stronger ignition with closer placement of the pan powder. Comparing the photos showing the close position and the “banked away” position shows a clearly stronger fire in the barrel and also traveling through the cleanout hole on the far side. While evidence continues to support a close priming of the pan, only timing of the positions will provide conclusive proof. That comes next.

Pan Vent Experiments — Introduction

Part 1 — Black Powder Ignition Characteristics

Part 2 — Initial Pan Experiments

Part 4 — Priming Powder Amount by Weight

Part 5 — Timing Powder locations in Pan

Part 6 — High and Low Vent Experiments

April 8, 2008
Part 4 — Priming Powder Amount by Weight

Determining the amount of black powder to be used in testing. Since flintlock pans are of different size, I felt that this was a necessary step in our process.

In this phase of testing I timed different amounts of priming powder. Ten amounts each of .5 grains, .75 grains, and 1.0 grains of Swiss Null B priming powder were weighed to the nearest tenth of a grain. These were timed in the fixture to see if varying the amount of prime affects the speed or consistency.

The fixture allowed the barrel to be rotated to vertical to load 15 grains of Swiss fffg for the barrel powder. The barrel was then rotated to level and the pan primed. Photo cells were checked to make sure they are pointed at the pan and the muzzle. The last step was to make sure the computer was ready. The pan was ignited with a hot copper wire and the readings recorded. The barrel was wiped between trials.

Photos of the fixture are shown below.

These two fixture photos also show the range of movement that can be used to test the location of the vent hole in relation to the pan. The top photo shows the hole in it’s lowest location, while the bottom photo shows highest location. For all tests so far, the vent hole has been centered on a line level with the top of the pan.

The graph below shows the trials with the three different priming powder amounts:

In evaluating the results of this test, I found Joe Sharber to be of great help. Joe, a fellow blackpowder fan with statistical experience, provided help with the number crunching. He pointed out that there is no statistically significant difference in the average ignition times. However he also noted that the variability or standard deviation was statistically significant.

Joe suggested that the term “Coefficient of Variation” * may be of value as a measure of consistency. The CV listed in the chart helps to show the advantage in consistency of the trials done with .75 grain priming powder. Because of this .75 grain will be the powder amount used in future tests.

* Coeficient of Variation is defined as 100 x (standard deviation divided by the mean). It is given as a percent. My thanks to Mr. Sharber for his assistance.

Pan Vent Experiments — Introduction

Part 1 — Black Powder Ignition Characteristics

Part 2 — Initial Pan Experiments

Part 3 — Photography through the muzzle

Part 5 — Timing Powder locations in Pan

Part 6 — High and Low Vent Experiments

April 4, 2008
Part 5 — Timing Powder locations in Pan

Is it better to bank the black powder priming away from the vent? This piece of conventional flintlock wisdom will be tested.

Part 5 of our test series will examine the question about where in the pan provides the best ignition. Conventional wisdom has told us that banking the priming powder away from the vent will produce the fastest ignition. Practically avery black powder shooter has heard this. This theory is based on human senses or what looks and sounds fast. The current test is designed to see if conventional wisdom is correct.

Early attempts showed a trend developing but had results that did not fit the rest of the range. A careful plan was developed to remove as many variables as possible especially those that were caused by fouling. Between firings the following were done:

The barrel was wiped. An additional step was added here and explained in the video.

A pan brush was used.

A pipe cleaner was used in the vent.

Compressed air was blown into the vent.

The priming powder used was Swiss Null B weighed on a balance scales. Since earlier testing showed its consistency, .75 gr was used. Because the placement of priming powder was the variable, care was used in its placement. The charge was poured into the pan and moved into the test positions using pencil with a rounded eraser. Powder could be pushed to the outer edge of the pan as well as very close to the vent. In both of these positions I felt that I was using more care in the powder placement than the normal firing of the lock in the gun. I realized that I chose the extremes in powder placement, and that a shooter would fall somewhere in between.

The tests were run in a 24 hour period with temperature controlled by thermostat. The day was picked with humidity in mind. The humidity varied within a range from 60 – 66 %. This is noted on the spreadsheets. Each battery of tests consisted of ten trials each – prime banked away from the vent, and prime placed as close to the vent as possible without covering it. To insure that no priming method had a unfair advantage, the trials were alternated so that a complete test battery included 10 trials each, alternated for a total of 20 trials.

At the end of the test session the ten trials for each priming method were recorded and all parts cleaned. Battery 1 was done in the afternoon at 60% humidity. Battery 2 was done in the evening at 66% humidity. The final battery was done the following morning at 60% humidity.

I made a short video that showed the processes involved:

The results are shown in the spreadsheet below.

The obvious conclusion is that banking the prime away from the vent doesn’t produce the most rapid ignition as we once thought. Banking the powder way from the vent actually reduced the ignition speed by 16%. This conclusion runs counter to conventional wisdom heard for years in muzzle loading circles. However, it is consistent with earlier tests where we saw photos with brighter fire from a close positioning of the prime.

While these results change the way I will prime my flintlock, there are other considerations that must be dealt with. In my tests the pan was ignited by a copper wire heated red hot. In the real flint world the sparks need a bed of powder on which to land, and this must be part of or priming procedure. This means that when I prime my locks, my emphasis will be close to the vent rather than away from it, but the bottom of the pan must have sufficient prime for sparks to land in. Thus, how well a lock places its sparks in the pan becomes an equally important consideration.

One other result of this experiment is that I have become increasingly skeptical of human senses in how I perceive flintlock ignition. And, there are more questions. What about low vent locations? This has always been rejected as a cause of slow ignition. Maybe we’re wrong about that as well. We’ll look at that in Part 6.

Pan Vent Experiments — Introduction

Part 1 — Black Powder Ignition Characteristics

Part 2 — Initial Pan Experiments

Part 3 — Photography through the muzzle

Part 4 — Priming Powder Amount by Weight

Part 6 — High and Low Vent Experiments

April 2, 2008
Part 6 — High and Low Vent Experiments

Low vs High Vent Test Phase . . . . Where should the vent be positioned for best black powder ignition? Again, conventional flintlock wisdom is tested.

Up until this phase of the experiments the vent hole has been located level with the top of the pan. In those trials other variables were being examined. In this phase, the location of the ventis the variable. The lock plate has been adjusted to place the vent at the bottom of the pan. Actually the outside edge of the exterior cone is at the bottom of the pan.

Most shooters with this vent location use care to avoid covering the vent. In the first set of trials I primed three different ways:

1. Prime banked to the outside

2. Prime level in the pan (I tapped the fixture to level the prime.)

3. Prime close to the vent and covering it completely.

The equipment used was the same: computer, physics interface, photo cells, and the fixture for holding the barrel and lock plate. The location for the photocells remained the same. Priming charges were kept covered until they were used.

The amount of the prime for this test remains .75 grain of Swiss Null B priming powder. (This amount has been shown to be the most consistent in previous tests.) The methods used are the same as in earlier tests. The video link below shows the process. (This is the same video as in Part 5.)

Because I was worried about fouling causing unreliable data, every effort was used to eliminate it as a variable. As in the earlier tests, the following steps were used to prevent fouling from affecting the data:

Wipe barrel between shots.

Second cleaning rod designed to wipe the vent liner.

Pan brushed.

Pipe cleaner used through the vent.

Compressed air through the vent.

While these steps may seem unnecessary for normal shooting, I felt justified when trying to obtain meaningful data.

Below is the data gathered for the low vent test:

It is worth noting that the trials covering the vent and the level prime were as close as they were. I suspect that there is no statistical difference between these two variations. Both, however were faster than banked away. They were 15-20% faster, in fact. I’ll draw no further conclusions until the high vent location is timed.

High Vent Test Phase

As I worked on the high vent phase, humidity became a concern. I was uncertain if I could maintain a comparable humidity when this phase was done. Earlier testing had been done with humidity in the 50-60% range. I waited for weather to help me, but found that by using an air conditioner in the garage I could keep the humidity within this range. Humidity at the beginning of the test was 58% dropping to 51% as the testing concluded. Temperature throughout testing was 63-64 degrees.

The only variable in this phase was the location of the vent. The lock plate and pan were rotated to place the vent as high as possible. The bottom edge of the exterior cone on the vent was well above the level of the pan. Please note the photo showing the vent hole.

The procedure was to time 15 tries with each of three powder locations in the pan – just as I did in the low vent tests. The tries were alternated as follows: powder banked away, level prime, and as close to the vent as possible. In this last location, I had intended to cover the vent, but .75 grain of powder was not enough with the vent located this high. I considered increasing the charge to 1.0 grains, but concluded that it would introduce another variable. I decided against that and used a pencil eraser to position the prime as close as possible.

After each location was timed 5 times, I removed the barrel and cleaned everything. Then I timed the next series. After 10 times I again cleaned, and then timed the last group.

The chart that follows shows the data gathered. As happened in the low vent trials, banking the powder away was slower and less consistent than level or close to the vent. Close positioning of the prime was decidedly faster and more consistent.

Conclusions:

These conclusions are those of the experimenter. You may have different opinions.

I wish to point out that every trial produced a report that sounded as one sound. The fastest (.032) and the slowest (.060) sounded the same. Even though one was almost twice as fast as the other, the sounds were indistinguishable. So my first conclusion is that the human eye and ear are terrible tools to use to evaluate flintlock performance. If differences can be determined by human senses, then the trial was indeed very slow.

The idea to bank powder away from the vent to improve flint performance is flawed thinking. In every test I conducted, the banked away trials came in last. Percentages varied, but banking the powder away was always slower. I found no evidence to support the old “bank the prime away from the vent.” (In the low vent test, banking powder away was 17% slower; in the high vent test, banking powder away was 23% slower.)

The idea that one should not cover the vent with priming powder because of having to burn through the vent instead of flashing through seems equally flawed. While I did not try to fill the vent, covering the vent did not cause slower times. The closer I could get priming to the vent, the faster and more consistent the results. In fact the consistency I found in positioning the priming powder close to the vent occured at all vent positions – low, level, and high.

The last conclusion involves the reason for this whole experiment – proper location for the vent in relationship to the pan. I found that the location of the vent in relation to the pan is far more forgiving that we have believed. Tests when the vent was extremely low or high both gave quick reliable ignition. A look at the chart below shows that all vent positions gave fast ignition when primed close to the vent (This is what we learned in the preliminary tests.) Also all vent positions gave uniformly poor performance when the priming powder was banked away from the vent.

————————–Banked way—————-Level Prime—————-Close prime

Low Vent—————–.046—————————.037—————————-.038

Level Vent —————.043—————————- * —————————–.036

High Vent—————–.048—————————.043—————————-.037

*I did not time level priming when testing the level vent/pan position.

I began this series of test thinking that the big variable would be the vent location. However, I am now concluding that it is of minor concern compared to the location of the priming powder in the pan. I still like a vent level with the plan flat won’t loose sleep over a pan a little high or low.

All of the work represented here was based on igniting the powder “artifically” using a red-hot copper wire. This was done intentionally to remove the variables in amount, quality, and location of the sparks. In reality the flint shooter must manage his lock to minimize these variables. Regardless of what the experiments show us, the shooter must place priming powder where his sparks will land. Time with his gun will determine this. However the shooter need not be afraid of priming powder too close to the vent – that is to be encouraged. It is far better to have the prime too close than too far away.

Pan Vent Experiments — Introduction

Part 1 — Black Powder Ignition Characteristics

Part 2 — Initial Pan Experiments

Part 3 — Photography through the muzzle

Part 4 — Priming Powder Amount by Weight

Part 5 — Timing Powder locations in Pan

April 1, 2008
Pan Vent Experiments – Continued

In my earlier article called “Pan Vent Experiments”, I examined powder placement in the pan and timed vent locations. I found that pan placement was far more forgiving that we thought. I found that a vent covered with prime did NOT slow ignition as we once thought. In fact priming powder located as close as possible to the barrel was the fastest way to prime. In this photo article, I will look at the possibility that a vent can be placed too high.

The series of photos included here are in response to comments generated in a number of internet forums the author reads. I have timed low, level, and high vent locations and found no significant difference in ignition times. Questions still surface about the preferred location of the vent. Until these ignition tests and these photos, all we had to go by was human senses. The best gun makers in the world early or modern had no better tools of discovery. Decisions they made were made without the benefit of an ability to test their theories. If the performance of the flintlock passed their “human sense test”, it was deemed correct. Now we can actually review their decisions about vent placement with test results they never had.

All earlier photos that I took were with the vent in the “level” position. The purpose of those photos was to examine other variables. Here the only variable will be the height of the vent. I took three photos at each of the following vent locations:

a. vent located .030” above the top level of the pan

b. vent located level with the top of the pan

c. vent in the bottom of the pan

The reason for multiple photos is that I hated basing any conclusion on only one trial. I set the camera to look into the muzzle. The aperture was f13 and the shutter held the lens open for 4 seconds. A cable release was used to make the operation easier. I primed the pan with the powder as close as possible to the barrel. Earlier tests showed this to be anywhere from 15-25% faster. In the low vent position the prime covered the vent. This is of no concern – contrary to popular belief, this does NOT result in slower times.

The vent locations were photographed three times with 1/2 grain of Swiss and ¾ grain of Swiss. These charges were weighted. The results of the different amounts of powder were very similar. I chose to upload the ¾ grain photos. Here are the photos of the vent .030” above level with the pan top:

Here are the photos with the vent level with the pan top:

Here are the photos taken with the vent at the bottom of the pan:

One additional photo was taken because most shooters use more priming powder that the ¾ grain used in this test. My pan charger is advertized to throw 3 grains. I used it for this final trial in the low vent position:

Conclusions drawn here are based on these photos and the data collected in the earlier article. A strong argument can be made for the level vent location used by the majority of flint makers. Numerical data supports this, and these photos show a strong flame moving through the vent. My rifles use this location and I see no advantage in changing them.

An equally strong argument can be made for the low vent location. The photo evidence also shows an impressive flame front to go along with good timing numbers. If my rifle had a low vent, I would not change it.

I question the location tested here with the vent located .030″ higher than the top of the pan. The flame traveling through the vent is noticably less than the the other positions. I timed a high vent position earlier, but I did not specifically set the vent to the 030″ position photographed here. Since high vent data gathered earlier was not precisely placed, it may not be valid here. Based on the weak flame seen inside the barrel, I tend to conclude that .030″ may be too high for best ignition.

March 30, 2008