AmericanLongRifles Forums
General discussion => Gun Building => Topic started by: Tommy Bruce on November 06, 2010, 02:07:04 AM
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I just finished no. 5 and am getting ready to drill the touch hole. Usually I just do a straight hole but was wondering if I used a counter-sink bit to make the hole a bit wider near the pan and then narrow on the inside of the barrel. Have any of you guys ever did this before? Did it increase ignition time?
thanks
Tommy
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I just finished no. 5 and am getting ready to drill the touch hole. Usually I just do a straight hole but was wondering if I used a counter-sink bit to make the hole a bit wider near the pan and then narrow on the inside of the barrel. Have any of you guys ever did this before? Did it increase ignition time?
thanks
Tommy
As a part of testing I did in Feb. 2000 Muzzle Blasts I timed a 1/16" straight vent hole with and without a mild exterior cone. I did 20 trials and recorded the average.
-----------------straight vent--------------------exterior cone (both 1/16")
Average:-----------.0440-------------------------------.0406
Variation:----------.0321-------------------------------.0278
In this instance both the average and variation were improved. The rest of the article timed straight vents - no others were coned. These tests are 10 years old, and we have since done tests of vent liners that have been quicker, however times in the low .0400's are very respectable IMHO
Regards,
Pletch
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Thanks Larry,
That's excellent information.
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Dan Caywood likes vents coned on the exterior.
I have a $#*! of a time getting my Caywood .62 cal fowler to do other than flash in pan. Great lock, though. I pick & pick, haven't figured out the right rhythm. Caywood .45 Southern Mountain Rifle works just fine so long as I pick the vent.
(sorry Mr. C.)
Mr. Pletcher this has nothing to do with time of ignition, just whether or not it goes boom vs puff.
Most contemporary guns I've had with those nasty stainless vents, coned from the inside, go off just fine. The one that didn't, a .40 Pedersoli rifle, worked fine when I switched from FFg to FFFg main charge.
Good English flint pistols had gold or platinum liners, I belieive coned from the inside, certainly not from outside. I think they might have known a bit about flint ignition, one's life depending on it at that time.
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-----------------straight vent--------------------exterior cone (both 1/16")
Average:-----------.0440-------------------------------.0406
Variation:----------.0321-------------------------------.0278
For these data, a one-tailed T test gives a P value (the probability that the means are different) of 0.358. To show a real difference between two means, the usual acceptance level for statistics is 0.05, or a 95% probability that the means a different.
0.358 is a long way from 0.05. We can conclude then, that there is no significant difference between these means, and adding an exterior cone will have no effect on ignition speed.
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I have coned form the outside for years. Works great for me.. Just my 2 cents.
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For these data, a one-tailed T test gives a P value (the probability that the means are different) of 0.358. To show a real difference between two means, the usual acceptance level for statistics is 0.05, or a 95% probability that the means a different.
0.358 is a long way from 0.05. We can conclude then, that there is no significant difference between these means, and adding an exterior cone will have no effect on ignition speed.
Man is that GREAT!!!! not the result, but rather that you reached an objective conclusion in a rational fashion using the only tool that makes sense. You just made my day!!!!
Brent
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TB,
I had a twelve guage NW trade gun I made. Drilled the TH just a little high through a thick chamber wall. I found coning the hole helped make it more reliable. If I combined that with punching a hole through the charge and pushing a little prime 4fg though the TH I had completely reliable and very fast ignition. I did not notice that the coning made it faster by itself, just more reliable.
volatpluvia
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My two cents over time and experience. If the barrel wall is thick enough, an interior cone is the ticket. Nothing has ever been made better the the Chambres White lightning. With a thin barrel (13/16 th .45, 7/8th .50, 15/16 th .54 ) a vent liner will be gas cut over time, and an exterior cone will work as well. Also I believe the smaller the hole you can get away with, the more consistent and thus the more accurate the result.
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A long time ago, I was advised by Lynton McKenzie that the touch hole liners he had seen on dozens of early English guns and rifles were invariably coned from the inside. I started making mine that way, and have seen no reason to change.
To work best, the outer edge of the coned hole has to be almost a knife edge, and when the gun is charged, you can see grains of powder peeking through the touchhole from the inside toward the pan. That touch hole conformation, combined with a touch hole location about 1/16" above the rim of the pan results in near instant ignition, every time.
This is, of course, the White Lightning conformation.
Bill
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I have never heard a satisfactory answer as to how you clean an inside coned TH.
When you slide a patch down, how does it get into that nice concave cone?
The only gun I have with a liner is my .45 1/18 twist bullet gun. That's because 80 gr of powder and a 535 gr bullet is hard on touch holes. I have to change the liner every match.
All my other guns have a 5/64th hole, with a slight outside cone. Easy to clean, and they are very reliable.
I suspect that this is one of those things that a lot of us are set in our ways about. ;D
For me, liners are for fixing a burned out touch hole. On round ball guns, I've not yet had to do that, and that's after more than a couple thousand shots on my .50 B weight swamped barrel.
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When I push a patched jag down the barrel the pressure blows any fouling in the interior cone right out the vent.... When I use tow, after scrubbing I fill the barrel nearly with water and push the worm and tow down fast..same flush of the liner as with the jag..... I can't see cleaning a coned liner as any kind of problem.
I try to follow Bill Brockway's method when building and locating the touch hole.
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Joe, Brent,
The T-score comments got me thinking through the straight vent results in the 2000 article. I went back and calculated T-scores on other vent diameter times. Comparisons showed that on vent diameters above 1/16” there were no significant differences. However if one compares times of smaller than 1/16” vents a significant difference is seen.
I appreciated Bill Shipman’s comments about the Chambers vent. I agree and use WL vents on my rifles. Regretfully I do not have a comparison of a Chambers liner with increasingly larger vent diameters. I did T-scores on Chambers vents with regard to vent location and priming powder positioning in the pan.
Based on T-scores and significant differences:
T-scores comparing high vs low vent positions show no significant differences. (In the low vent position, the vent was covered with prime.)
T-scores comparing the location of priming powder showed a significant difference. (Prime close to the barrel vs banked away)
I suspect that as a statistical light weight, I should stop here. However, from this afternoons work, my gut says that placement of priming powder is of greater importance than either vent position or vent diameter.
One last thing: Is there a statistic that can be used to indicate an uncontrolled variable?
Regards,
Pletch
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One last thing: Is there a statistic that can be used to indicate an uncontrolled variable?
I’m not sure what you mean. Can you give a specific example?
However, from this afternoons work, my gut says that placement of priming powder is of greater importance than either vent position or vent diameter.
That is the correct statistical conclusion. All your tests are well designed, have large enough sample sizes, and were meticulously conducted, so I think your results and conclusions are reliable. Excellent work Larry.
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Tom,
Best best-shooting guns I have ever built all have internal cone vent bushings - bar none. If your intent is the build the best-shooting gun you can build, I believe you should seriously consider using a vent bushing (liner). On my most recent build I used the While-Lightning vent bushing from Jim Chambers Flintlocks and the installation was quick, easier than my other way and the rifle SHOOTS!
But I'm from New Jersey - what do I know?
Best Regards,
JMC
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One last thing: Is there a statistic that can be used to indicate an uncontrolled variable?
I’m not sure what you mean. Can you give a specific example?
That is the correct statistical conclusion. All your tests are well designed, have large enough sample sizes, and were meticulously conducted, so I think your results and conclusions are reliable. Excellent work Larry.
That question was a shot in the dark. I was wondering if those used to stats could look at a score or group of scores and see a flaw in methodology - perhaps an unaccounted for variable or inadequate control of an known variable. My limited knowledge of stats prevent me from doing that. My technique is to exhaust all means to control variables because I don't have a way to predict how successfully that's done.
Regards,
Pletch
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You can’t really look at data and infer a whole lot about methodology. Your methods are very good, and probably can’t be improved on.
However, you can infer some things about uncontrolled variables by looking at data. One of the striking features of your data sets is the high standard deviation, or high variability if you prefer to call it that. As a general rule, statisticians get uneasy when the standard deviation is more than half of the mean. Without going into too much detail, when the variability is that high, the data are often not normally distributed. It can be normalized by transforming the data, and doing statistics on the transforms. For example, square root or logarithmic transforms are commonly used to make data behave better. These techniques are not really necessary for your data though.
High variability can be a result of an uncontrolled variable or it can be an accurate representation of the feature you are measuring. I’ve thought about your data a lot, and I think that the variability is caused by one (or both) of two things: variability in how the loose powder in the pan ignites and spreads the flame front; or variability in how many sparks land on the powder and where they land. If I had to guess, I’d guess that the latter is the most likely cause.
I think you could test this hypothesis quite easily. If you used a uniform source of ignition, perhaps a nichrome wire, you could see how much the variability decreased. Any decrease in variability could be attributed to a spark effect and the remaining variability would be due to spread of the flame front.
At risk of getting flamed myself, I think that I could make a stronger argument for minimizing lock time by keeping the flint sharp and the frizzen hard, than I could for preferring a coned vent over a straight hole. I’ll try and get some time in the next few days to crunch the numbers and show you why.
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I would have to second Bill Brockway's post, for all the reasons he states.
As far as cleaning an inside cone...
My method over the last 32 years, has been to plug the touch hole and fill the breech with some cleaning solution and let it sit while I clean the lock. I then drain the solution from the muzzle and flush any remaining soln. out the touch whole with a wet patch on a cleaning jag...
A few more wet patches, then dry and oil.
This has worked great for me all this time, and I might add all my shooting during this time has been with just two barrels, the second of which is still shooting better than I can hold.
Jeff
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After about 40 years of shooting flintlocks, most of which had an internal cone, I have never worried about cleaning the inside of the liner. Nor have I had any trouble because of it. I work to get the bore clean and scrape the plug.
Bruce
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I have never heard a satisfactory answer as to how you clean an inside coned TH.
I was wondering about this and came up with this tool. With my limited experience I dont know if it has been done before, i cant see why not. I use both ends, one to straight pick the vent and the other end I "fish" in thru the vent and rotate between my fingers...fwiw....... Kerry
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi52.tinypic.com%2F21cih45.png&hash=a0fbd7a1c9fce352b2543bee3009d079305de164)
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I clean my rifleguns by laying them down on a table, vent down. that way the fouled water squirts down-ward while cleaning, onto some paper towels. During the cleaning I tilt the muzzle up a few degrees and use an ear syringe to squirt a shot of water down the bore. I immediately blow down the bore as hard as I can which shoots a stream of water out the vent - cleaning the vent interior. I have disassembled guns cleaned this way and found teh vents perfectly clean.
Best Regards,
JMC
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I clean my rifleguns by laying them down on a table, vent down. that way the fouled water squirts down-ward while cleaning, onto some paper towels. During the cleaning I tilt the muzzle up a few degrees and use an ear syringe to squirt a shot of water down the bore. I immediately blow down the bore as hard as I can which shoots a stream of water out the vent - cleaning the vent interior. I have disassembled guns cleaned this way and found teh vents perfectly clean.
Best Regards,
JMC
I would have to agree.
A good dose of water will clean the vent. BP fouling does not require a lot of scrubbing to remove.
My Nock breech rifle has a hooked breech and when cleaned in a small plastic bucket of tepid water the antechamber is perfectly clean if I pull the clean out.
Dan
Oops.
Should read "if I pull the clean out to check". Which I seldom do.
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Pile cleaners also work to wipe out the touch hole.
Tom