Breech testing continues - Cupped breech inferior

[rich pierce]

That's the real trouble with doing experiments- living with the data.

[Dphariss]

DP
I really like the Nock breech and would not change it. I guess i should try some Goex in it as well.

Dan

[Dphariss]

That's the real trouble with doing experiments- living with the data.

I was sure this testing would produce some surprises. Had to. The electronics are not susceptible to "feel" or "interpretation".
Can't wait for more data...
Dan

[Larry Pletcher]

That's the real trouble with doing experiments- living with the data.

I was sure this testing would produce some surprises. Had to. The electronics are not susceptible to "feel" or "interpretation".
Can't wait for more data...
Dan

Dan,
This Wednesday looks like our next day to work.  This will be to finish the WL liner that we didn't get to a clean set of trials with the cupped breech.  (I think thats right.)  Then we'll start the Nock breech testing.

In between times we're getting another topic ready.  It will be a comparison between a flint (small Siler), percussion (small Siler), and a mule ear Siler plate).  these will be mounted in a Chambers pistol kit stock.  We'll time from sear trip to photo cell at the muzzle.  (A car door solenoid will fire the sear and start time.)  This actual tesing is down the road a ways, but the physical parts and fixture are in progress.

Regards,
Pletch

[Daryl]

I am really looking forward to the pistol stock, Larry.  I have a John Bailes lock on my Fling handgun- don't event ink I remembered to show Dan that one- maybe next time- HA!  The point is, with a sharp flint and it's .070" vent, ignition is everything the ignition is on my large Dickert rifle lock. That Dickert rivals all of the fastest Chamber's Silers I've seen, and they are fast - Taylor concurs.

[Larry Pletcher]

I am really looking forward to the pistol stock, Larry.  I have a John Bailes lock on my Fling handgun- don't event ink I remembered to show Dan that one- maybe next time- HA!  The point is, with a sharp flint and it's .070" vent, ignition is everything the ignition is on my large Dickert rifle lock. That Dickert rivals all of the fastest Chamber's Silers I've seen, and they are fast - Taylor concurs.

Ya, I'm looking forward to this one too.  Conventional wisdom would probably say:
1. mule ear perc.
2. standard perc.
3. Flint

But----- I'm getting more and more skeptical about "conventional wisdom".   We've believed a bunch of stuff based on human senses that we only thought were true.  Oh well, that's what makes this fun.  Besides, no one has ever collected numbers on a flint vs percussion "race" that I know of.

Regards,
Pletch

[Sam Everly]

It could be that with a cup it makes the vent hole more in the middle of the charge . Or it has to burn the powder from the center of the charge. Where a flat breech puts the powder to where it burns from the rear towards the front. It would be easy to see if this is what is going on . Just cup the breech you used deeper . You should see by doing this , if that is it should be worse. That could be why a Knocks breech is better . It burns from the rear , forward.           

[Larry Pletcher]

It could be that with a cup it makes the vent hole more in the middle of the charge . Or it has to burn the powder from the center of the charge. Where a flat breech puts the powder to where it burns from the rear towards the front. It would be easy to see if this is what is going on . Just cup the breech you used deeper . You should see by doing this , if that is it should be worse. That could be why a Knocks breech is better . It burns from the rear , forward.           

Good thoughts, Sam.  We speculate that less than 1/4 of the charge was in the cup - maybe less.  But we haven't measured that.  When we get going this week, we should remove the breech and see how much powder it will hold.  I agree that if that is the reason, then deepening the cup should result in an increase in the time.  Thanks Sam.
Regards,
Pletch

[northmn]

I am not married to the concept of a cupped breech.  I like them for geometry in build so that I can use the "square" breech plug as the barrels are designed for.  I one looks at pictures of originals, the vent and lock are back further than on modern guns.  Some even allow for clearance of the vent in front of the breech plug wihich increases the position even more.   Some originals actually had a groove cut in the breech plug to permit rear burn.  In other words if what Sam says is true, which is theory only, the use of a cupped breech in which the vent is positioned more at the rear should be quicker.  Another option would be to shorten the breech plugs, which is probably not as dangerous as it sounds. 
Good luck on your lock comparison tests.  This opens all kinds of issues.  The English locks using a stirrup system on the tumbler were considered faster than the little Siler even, etc.  Even in percussions the hammer throw was lessened over time, etc ad nausium.  In other words, total ignition time from trigger pull to bang is a combination of ascetic design, ie using an old time design and lock, and a little science.

DP 

[Dphariss]

It could be that with a cup it makes the vent hole more in the middle of the charge . Or it has to burn the powder from the center of the charge. Where a flat breech puts the powder to where it burns from the rear towards the front. It would be easy to see if this is what is going on . Just cup the breech you used deeper . You should see by doing this , if that is it should be worse. That could be why a Knocks breech is better . It burns from the rear , forward.           

Actually, according to some at the time, the Nock was intended to shoot a jet of fire into the powder charge making it burn faster. Thats one explanation any way. It also was intended to prevent powder packing at the vent, which it does and this increases flame speed and to reduce the powder blown out the vent as the pressure builds?
Note that some of the opinions of the time circa 1780-1830 were based on what is today "junk science" guesses and opinions.  This applied to all facets of interior/exterior ballistics so there was a lot of "facts" promoted by "experts" of the day that are laughable now.
This is one reason the ongoing tests are important.
Like all such things they will not be an end all accumulation of data. There are just too many variables. But they certainly add immensely to the data available which, aside from Larry's other tests and perhaps a thin smattering of stuff from others there was NOTHING. The two doing the work are answering a lot of questions and creating others just as all experiments are prone to do.

Dan

[northmn]

The more I think about Sam's theory the more I think he is correct.
A story a proff told us about research.  It seems there was esearch done on a trained flea.  It would jump to a whistle.  They cut a leg off and it hesitated slightly and jumped.  They cut another leg off and it still jumped but not as high and with hesitation. And so forth until they cut the last leg off in which it did not jump at all.  The conclusion was that fleas must hear through their legs as they get progressively more deaf as you cut off their legs.
While the conclusion is of course ridiculous, the point is that while data may be reliable, we have to be careful about conclusions and explanations.  Its like the priming results, closer priming was quicker as it did not have to "jump" nor fuse to get to the vent. It makes sense and is explanable.  Sometimes research seems to explain the obvious.  In this case there are questions.

DP

[Mad Monk]

Actually, according to some at the time, the Nock was intended to shoot a jet of fire into the powder charge making it burn faster. Thats one explanation any way.

Dan
[/quote]


Dan,

This comment reminds me of the work I did with my percussion rifle looking at the claims then being mde for various brands of percussion caps.
The CCI Magnum caps were claimed to give 20% more flame compared to a standard cap.  Then Remington claimed that their "Black Powder" caps gave 40% more flame compared to a standard cap.
What I found in the lab was that this increased flame was simply a thing of how much more of the primer composition was being added to the caps.  When I looked at this over the chronograph I found that the increased amount of flame produced by the caps jumped up the muzzle velocities.  Then when I switched to the 209 primers there was no increase in velocity.
So what I found was that like smokeless powders, black powder also exhibits a "sensitivity to intesity of ignition".  By the standards of that time a jump in muzzle velocity would be viewed as an "increase in hit" produced by the more intesnse and therfor faster ignition through the powder charge.

But this increased ignition speed through the charge depends a good deal on the amiunt of space between the individual grains of powder and the size of the spaces between the grains.  In military terms this is described as "propellant bed porosity".

I am reminded of work done by Col. Vaughn Goodwin at Aberdeen Proving Ground back in 1975 when he was then looking at a target grade powder that GOEX was trying to sell to the bench gun shooters at friendship.  This "target grade" powder was nothing more than regular production powder screened to a more uniform grain size.  Col. Vaughn ran pressure bomb tests on it and showed me the pressure graphs.  In these pressure bomb tests they look at the time from when the igniter fires until the peak pressure is seen in the bomb.
He ran 1f down to 5F in grain sizing.  As he went from 1F down to 2F the length of time to peak pressure went down a bit.  Then switching to 3F he saw another drop in time to peak pressure.  Dropping down to 4F produced another reduction in time to peak pressure.  When he switched to 5F powder the time to peak pressure went up rather than down.

So the idea of shooting a jet of flame into the powder charge by a small charge in an ante chamber may have merit.  As ong as the "igniter charge" is not large enough to inject a large amount of gas that would simple move the projectile and thus disperse the mass comprising the main charge.  In other words.  There may be a point in that concept where it becomes counterproductive.

E. Ogre

[Dphariss]

Ogre
In reading W. Greener (circa 1830) we find that he thought that the powder packed against the base of the bullet/shot charge by chamber pressure was so compressed together that it burnt like a rocket motor.
This bit of "science" might be why the Nock breech was thought up. Or it could just be Greeners idea. He promotes some fairly strange stuff. Like allowing a barrel to simply recoil into a pile of sand produced less pressure during proof then having the barrel fixed so it could not recoil.
He was commenting on barrels failing with service charges after proof. Not understanding crappy steel/iron being a factor.
So I hesitate to quote as *fact* many things I find in historical writings.
However, as you point out the jet of flame is viable. The relatively loose powder in the antechamber will ignite slightly faster due to space between the grains and this could produce a pressure jet to the main charge and possibly get the projectile out the muzzle faster. The primary concern for the English wing shooter and apparently the reason for most of the patent firearms improvements during the 1780-1830 period.
Dan

[northmn]

Its interesting that the phoney powders using the 209 primer have led to the development of a softer primer which supports Monks statements. I have seen shotgun loads using too hot a primer that supposedly pop the crimps before full ignition and cause bloopers.  In most cases the utilization of various systems became popular because they worked However utility can take many forms.  The Nock breeches on double shotguns permitted slimmer profiles and easier hammer reach.  Patent breeches were almost indestructable as compared to the drum systems.  You also get into an issue of reliability vs speed.  A reliable ignition does not have to necessarily be a faster one.  I would suspect fusng priming powder into a vent is very realiable.  It is also very slow. They have been working on getting the ignition at the base of the load in ML's since GG grandfathers day, under the theory that it is better ignition and more accurate.  Were they wrong?

DP     

[Larry Pletcher]

Good Morning,
I appreciate all of your thoughts.  One of the cool things about ALR is the ability to pick the brains of folks all over the country.  Collectively the experimentors have the advantage of very knowledgeable shooters offering helpful advice.

I think Northmn had a valid comment about drawing conclusions.  For instance one might be tempted to conclude that the cupped breech placed more of the charge behind the vent.  If you noticed when Sam suggested that he said, "it could be that...." and then he offered a method for confirm that idea.  This is what I like about ALR.  BTW when Steve and I spoke last night, he mentioned that the cupped breech depth was measured at .125 in the center.  (If I would have thought, I should have simply asked Dan how deep he cut it.)  Steve went on to say that he could deepen the cup to 1/4" and then we could retest.  We want to measure the amount of powder the breech holds before we do that though.  Since we're using 20gr in all tests, we will be able to know exactly how much powder is behind the vent.

As far as conclusions on the breech experiment, I'm likely to report the numbers, offer a possible reason for the data, and let the reader "jump" to his own conclusion.  My reluctance here is not because I mistrust the numbers, but because there are so many variations in ways these breeches could be designed, built, and (above all) how they are used or abused.

Dan raised a valid point when he said that there are simply too many variables involved and that experimentation always brings more questions.  Every time Steve and I get together someone eventually says, "You know we really should test .  . . . ." 

Bill, you realize that you were one of the encouragers that got me started on this.  I still have the papers you sent me in the late '80s.  Gary B was the other; his gentle push and his help with editing made a difference.

Regards,
Pletch

[roundball]

And all Flintlock users are benefactors of your unselfish willingness to share the results of your personal time, money, and skills...the tests have truly been outstanding, eye-opening, etc...if there was a "Significant Contribution To Understanfding Flintlock Operations Award" you would definitely deserve it !
 

[northmn]

Larry, I am not passing off the conclusions you have drawn as much as I wish there was a reasonable explanation.  The differences with a clean breech and the Dphariss vent are .0042 sec which is almost insignificant.  In the White Lightening the increase is .006 sec.  It seems once fouled neither vent system has an advantage.  I may make a square bottomed bit and ream out my current project as it would not be that difficult.  In addition I am going to try to make sure that the vent hole is at the bottom of the breech.  I am in no way belittling what you have done, there is something there.  I just have this nagging thought that there is a variable being missed.  The position of the vent may be more important than one thinks.  Many often drill the vent insert in front of the breech plug to clear it.  I am wondering if the "bottom" ignition may not be quicker.  There is a suggestion in your findings that it is so. 

DP 

[Larry Pletcher]

Northmn,
I take no offense with your comments.  I think it will take more tests to make me feel confident in drawing a too much from this.  Also your thought about "statistical significance"  is work noting.  Most of the numbers drawn from one test would fit in the range of the other.  In one case the numbers were both in the same range but one set was faster because the range where it was most consistent was lower that the other's.

Regarding teh cupped breech, after we measure how much powder it holds, Steve will likely deepen the cup - perhaps from 1/8" to 1/4".  If that step increases slows the times, there may be a trend.  If in doesn't, then add to the statistically insignficant catagory.

You also mentioned that the position of the vent maybe more important than one thinks.  I assume here you mean distance away from the breech plug.  Looks like more tests called for.  It would be interesting to set up a barrel where, after timing the vent at the breech, it  would be plugged and another installed at the front of the charge and timed again.

Regards,
Pletch

[northmn]

As to significance I feel you have established statistically significant differences in your trends, but there is another.  We are talking here about differences of maybe at most .008 of sec and in some cases less.  We are also looking at one aspect of the total igniton time as defined as to when the trigger is pull until the gun goes bang.  This includes the length of time fo sear sisengagement, hammer travel time as well as frizen travel, time for sparks to ignite the primer and so forth. 
We are entering into the domain of creating the "ultimate" flint target rifle.  Similar to the benchrest, X stick, chunk shooters looking for any edge they can get as in building underhammers and even some earlier than some of you know the inline actions.  We also have the stirrup linkage on locks to give quicker hammer time as well as enough snap to permit short throws.  Whether a Brown Bess has a cupped or flat breech would not matter much as you can just about time its total ignition time with a stop watch.  As long as I can remember the small Siler was recommended as being "faster" than the big one.  I have picked the English rainproof style late lock for my latest English styled sporting rifle  project because they are a faster lock using a small flint and a stirrup linkage system for a shorter throw.  I may square up the breech plug because your results and it would now be easy to do.  The location of the touch hole in regards to the lock will be such that I can fill the pan and not get a fusing effect, the frizen has a protuberence that fits into the pan to permit this and still cover the touch hole.  This total system might be faster than a classic long rifle using a large siler lock.  I do not know at what level of time the human system can sense or react to.  Falling plate pistol shooters used revolvers because they were faster than semiauto cycling time,  IPSC shooters switched to 38 Supers and other types becasue they did not want to wait for a 45 to cylcle.  Whether the .006-.008 of a second difference is significant is not known, it is probably more of a contributer than important of and by itself. 
I now have to go out and clean up more of that beautiful white s---- that has just been dumped on us.  Getting cabin fever and windy.  Getting ready to move south.

DP

 

[Daryl]

Vent position- yes - where to put it?  If the centre of the vent is at the face of the plug, then the rear of the vent is some distance behind the front threads of the plug which reduces the # of threads engaging the barrel at the vent's postion. 
Thus positioned, the vent exposes threads of the plug to hold and build fouling- another negative of having the vent's centre at the plug's face. If threaded to barely touch the face of the plug, having a 1/4" to 3/8" vent liner puts the centre of the vent well ahead of the plug's front face, .125"  to .1875" thus not igniting the powder at the very rear corner of the charge.  Although this isn't far, it's likely to be equivalent to a cupped breech face of at least .0125" depth,  concerning where the powder charge gets ignited.  Of course, having a fixed location for the vent for all tests would show if there was a change in plug shape's ignition timing - I guess - I'm getting a headache.

[Mad Monk]

Let me add this.

The idea of igniting the charge at the rear versus the middle versus the front has been a debate for a long time.  They even got into that with bp cartridges running a tube from the primer up through the charge to near the base of the bullet to ignite the charge.

Again.  This is based on the idea that when the charge ignites a portion of the charge is pushed along behind the moving projectile burning more like a rocket motor than in what is commonly called a fluidized bed state.

That has been shown to be questionable at best.  The flamespreading through the charge of powder is way faster than the initial movement of the projectile.  In most cases the charge is entirely ignited before the projectile has moved any distance from its point of rest on the charge.  In essence, it really does not matter where the point of ignition is in the charge.

I am reminded of the military work on the 155mm bagged charge.  Up into the 1980's the 155mm gun loading used a central charge ignition.  A long tube full of black powder extended up through holes in the center of the bags of smokeless.  Called a "snake" in the Aberdeen papers.  The 155mm bagged charge was switched over to "base pad" ignition by around 1988.  That would be a flannel bag containing black powder affixed to the rear face of the smokeless bag next to the initial primer mounted in the breech block.  This switch was considered to be an improvement in the interior ballistics in this large-caliber gun.

When I set up my .45 caliber Getz barrel in my shimmel I located the vent right on the face of the breech plug.  When I drilled the side flat for the vent it formed a groove in the face of the breech plug.  Little did i realize that I was thus setiing up ignition problems.  When I would shoot and then damp swab the bore the cloth covered jag would pack fouling around the joint between the barrel and the breech plug.  Just a thin ring around the joint.  This acted to partially block or restrict the vent hole.  Ignition slowed and became erratic.  If I had it to do over again I would have located the vent a little off the face of the breech plug.

E. Ogre

[northmn]

I have read studies concerning frontal ignition.  Apparently it has never impressed anyone enough to utilize it.  From what I gathered it was supposed to give less shot to shot variance.  The study I saw was very inconclusive.  It did not have anything to do with ignition time as much as burn rate.  Theoretically the ignition time is increased by the length of the flash tube.  You kind of reinforced my point in that reliability and speed are not the same thing.  I could as stated fuse every load, pick the vent and push in primer to guarantee contact with the charge and with good spark not get a flash in the pan.  It would also make for a very slow ignition.  A lot of what we do is compromise.

DP

[Dphariss]

<Snip>
  The Nock breeches on double shotguns permitted slimmer profiles and easier hammer reach.  Patent breeches were almost indestructable as compared to the drum systems. 

<Snip>
DP     

The *recessed* breech narrowed the gun. The Nock breech predates the recessed breech by at least  a decade. The recessed breech was a Manton invention.
The breech I sent to Larry is a Manton style recessed breech that has the Nock interior.
Dan

[Dphariss]

I read somewhere of frontal ignition tests with the 50 BMG cartridge failed due to extreme pressure problems. Possible poor ignition of the grey powder charge. Seems like Elmer Keith was involved during WW-II. Blew up some stuff IIRC and it takes some work to blow anything made for 50 bmg. Suspect poor ignition of the powder.
The Dreyse Needle Gun used frontal ignition of the BP charge successfully, well there were problems but not with the front ignition itself.
Frontal ignition in small arms in not really practical.
The artillery boosters  Ogre was discussing is a way to ASSURE reliable ignition of the charge. Poor ignition of smokeless powder is VERY bad can can result in extreme changes in burn rate and pressure developement that can blow parts over a wide radius. Testing some years back with a *reduced* charge of the normal powder that did not properly ignite blew a 250 pound breech piece of a field piece 1/2 a mile according to a reliable report.

BP does not do this, its not capable due to its chemical makeup.
Reduced charges of black, if "loose" may ignite faster and might give more pressure than expected for the weight of charge but the powder will not go out of control and detonate as nitro based smokeless can. Compressing BP heavily can add to "load inertia" and result in smaller velocity variations. But excess compression can produce its own set of problems especially with hard, dense, fast powders like Swiss.
Primers can and will blow projectiles out of the cartridge case before the power really makes pressure. Smokeless primer are pretty hot stuff and can blow a 500 grain 45 caliber bullet an inch or more up the bore with no powder at all. But this is not really applicable to caps and BP shooting. I have never seen BP fail to light off because the primer was too hot and I shot a LOT with the hottest primers we could get at one time.
Back to flint...
I am not sure what the Nock breech actually does or if it does much of anything different. Needs testing...
IF it makes significant pressure in the antechamber it should speed the burn of the powder in the barrel and/or breech chamber. Its not front ignition but it may give something closer to the way percussion performs. IE faster pressure rise than flint.
?

Dan

[northmn]

In the studies I read on shoulder arms, ie 30-06, they felt that the frontal ignition may be turning 4831 into 3031 as to burning characteristics, which would increase pressures.  I learned something as I thought Nock breeches were used in recessed breeches or the system anyway.  One reason I do not contribute a lot in the Antique arms section.  One of the reasons I have wondered about the conclusions is the fact that given the same wall thickness and everything els, if the cupped breech is slower and the flame is reaching the powder at the same average times, then it had to take longer for measurable ignition to occur.  Does the breech slow it down or the volume behind the vent?  I have built most of my rifles with bottom igniton.  When loading I have left the vent pick in the vent and withdrawn it to prime.  3f can be self priming so that it blocks that feature as when loading the powder compresses enough to remain in the barrel (I only seat srong enough to guarantee full seating)  It also made for more consistant ignition.  Also as mentioned, I found that it seemed that certain reasonable charges seemed to "blow" the vent clean.  Heavier ones of course fouled more, but it seemed too light, while not impeding loading like the heavy ones built up in the breech vent area.  As to whether that made for faster ignition when working correctly, I cannot say.  I have always wondered if the counter bored vents didn't foul enough to act like straight vents and Larry's pictures tend to support that.

DP