Breech Experiments

[Larry Pletcher]

Thanks, Chuck,
I appreciate all the knowledge I can pick up.

Roundball,
I'm not worried about the PC stuff on liners, at least not yet. 
When I timed cylinder holes I wanted to follow that up with liners that were currently available.  Yours fits that goal.  I'm having too much fun learning to let that get in my way.
Regards,
Pletch

[Acer Saccharum]

Nock's patent breech may have less loss out the touch hole than a standard breech.

Any time a gas goes from one volume to another through a restriction, you have a drop in pressure. Once the antechamber goes off, the main charge is ignited, with a subsequent rise in pressure. The pressure in the main chamber will push the ball out the bore, with equal pressure at the orifice of the antechamber. Going thru this orifice, the gas suffers a pressure drop, which means that there would be less pressure at the touchhole than there is in the main chamber.

Larry, can we hook up pressure transducers, too?

Acer

Oh, I was kidding about the transducer part.

[Rich Jakowski]

It will be great to watch the progress of this study, and it makes me wonder if after a 150 year gap the pinnacle of muzzle loading design will be achieved in the 21 century?

[Acer Saccharum]

We have the technology.

We have the ability.

Will we be able to surpass what has been done already? I don't rightly know. The guys who made these improvements in the early 19th Cent were geniuses, standing out in a world that had countless souls searching for the same answers. I can hope that at the very least we pay these men and their ideas homage, and gain some understanding along the way.

I do think that this high speed gizzie that Larry so generously records locks and ignition characteristics of powders, etc, is a definite edge over any quantitative tool the men of the Late Flint Period had.

[roundball]

Larry, the new liner is in the mail to you...don't even think about retrurning it...just keep it for possibloe use in the future...I appreciate all the terrific test results you've shared over the past couple years...not only the textual form of the test results but the slow motion videos-of-a-lifetime are simply outstanding.

[Acer Saccharum]

More thoughts on breeches. No, I don't stay up all night thinking about this stuff. Gun stuff is soooo boring to dream about. I'd rather be sleeping.

What do you think about these different styles of breeches? I thought we were going to test a flat breech, but after drawing this up, my thoughts tend toward chambered breech and Nock, mainly to get the same LOADED length on the barrel, see below (dims X and Y).


The alternative, which is definitely worth considering, is to use TWO DIFFERENT BARRELS, one cut for the Nock, and one cut for the flat breech. This would allow us to get the same loaded length. The variable would be that the bores could be slightly different, even if cut from the same blank.

[Benedict]

More thoughts on breeches. No, I don't stay up all night thinking about this stuff. Gun stuff is soooo boring to dream about. I'd rather be sleeping.

What do you think about these different styles of breeches? I thought we were going to test a flat breech, but after drawing this up, my thoughts tend toward chambered breech and Nock, mainly to get the same LOADED length on the barrel, see below (dims X and Y).

Acer, does this mean that you thinking of NOT testing the flat breech?  I am not sure that it does but I wanted to say that I think that it is extremely important that a flat breech be included in the test.  Most of our guns have flat breeches and knowing how much better, if any, the other breech designs are is, to me, the whole point of this series of tests.

If I misunderstood you comment, I apologize!

Bruce

[Acer Saccharum]

Bruce, I am just blabbering away, putting ideas out there. Yes, if we don't test the flat breech, what's the point of all this testing?

Look at the bottom of my last post, where I talk about two different barrels. I think this is the way we are going to have to go. Two barrels. The flat breech will require a touchhole IN the barrel itself, which will make it unsuitable for using on the Nock breech.

That's how I think it will have to go. Two different barrels, each one trimmed to the same loaded length.

Has anyone heard of the Nock breech being unsafe, since it has the small antechamber, which could have high initial pressure. Comments and suggestions welcome. Also note that the drawing I have done is just a sketch, the proportions and dimensions need to be defined and refined.

[Larry Pletcher]

Acer,
Since you mention barrel length, should we measure from vent hole to muzzle or from breech face to muzzle?
 
In my mind I was thinking about doing the flint breech and then cupped (dished) by removing and cupping the same plug. 

Just more things to think about.

Pletch

[rich pierce]

I can see the reasoning for keeping the ball to muzzle distance the same.  On the other hand, the shooter probably cares most about which breech "shoots fastest" with the same overall total barrel length (including the breech).  In other words a patent breech is considered part of the barrel and contributes to its length.

[Benedict]

Barrel length is a tough one for this test.  I think that for timing purposes having the ball to barrel end the same makes the most sense because then the distance the ball travels is the same.

Bruce

[Acer Saccharum]

Rich, Larry, I am not sure what parameters we need to watch for consistency, but I will try to esplane myself more clearly.

My direction has been this: Pletch will time the vent flare(indication of main charge igniting) to the ball leaving the muzzle. For consistency's sake, I think that the ball should be the same distance from the muzzle in all the different breeches we test. So ball travel in barrel time will be out of the equation.


Problem:
Since the Nock has a smaller chamber than the Plain breech, I am estimating that the ball will seat closer to the muzzle than in the Plain breech. If the same barrel is used for each test, then the loaded lengths will be different for each style of breech.

Loaded length: This is the distance from the muzzle to the top of the ball.

[Benedict]

Another thing to think about in regards to "loaded length" is that all the breeches are different and that you may need a separate barrel for each one.

Bruce

[Acer Saccharum]

Another thing to think about in regards to "loaded length" is that all the breeches are different and that you may need a separate barrel for each one.

Bruce

That's what I said....only in a more confusing manner, and with a lot more words.


Now, here's an idea. Same barrel. Do all the testing on the Nock. Record the 'loaded length' of the Nock. Then set up to do the flat breech. Make note in the difference of the 'loaded length' , and trim the barrel to the same dimension as the Nock length.

Acer

[Larry Pletcher]

Rich, Larry, I am not sure what parameters we need to watch for consistency, but I will try to esplane myself more clearly.

My direction has been this: Pletch will time the vent flare(indication of main charge igniting) to the ball leaving the muzzle. For consistency's sake, I think that the ball should be the same distance from the muzzle in all the different breeches we test. So ball travel in barrel time will be out of the equation.


Problem:
Since the Nock has a smaller chamber than the Plain breech, I am estimating that the ball will seat closer to the muzzle than in the Plain breech. If the same barrel is used for each test, then the loaded lengths will be different for each style of breech.

Loaded length: This is the distance from the muzzle to the top of the ball.

Acre,
The photo cell that starts time will be picking up pan ignition.  So the elapsed time will include from pan ignition to fire at the muzzle.  It would be helpful if one could separate pan ignition from the jet of gas coming from the vent, but by the time that occurres the photo cell will have already fired with pan ignition -- that all make sense??  

One possibility is that minor variations in barrel length may or may not be significant.  The difference may actually fall within the range caused by other variables.   For instance if one barrel arrangement is 1/2 " longer, flame would have to travel 1/2" at what -- 1000fps?? ------   That would be .00004 seconds.  Barrel length that is reasonably close may be just fine.  Gotta think on that some more.

Regards,
Pletch

[Jerry V Lape]

Maybe there is another way to measuring the same thing?   Instead of measuring the ignition flare to muzzle exit of the ball drill small holes on the muzzle end to create a second flare as the ball passes.  Measure time from ignition flare to muzzle flare.  Drill  small holes, about 1/16"diameter on the muzzle end of the barrel such that they are equal distance from the front of the ball for the various setups.  Thread the hole when you are done with it and screw in a plug before drilling the next hole for the muzzle flare.  With a well patched ball the muzzle flare should give you the midpoint of the ball at the time the flare begins.  Start the drilling for the setup with the longest load first so the holes will move from muzzle toward the breech for successive setups.  This way the hole won't be a factor  with the next shorter measurement and you won't have to worry about a smooth interior surface of the plugging screw as it will be downstream from the test.

[Acer Saccharum]

Sorry if I'm overthinking. Doesn't happen often, so it's a rush when it happens.

[Roger Fisher]

Bruce, I am just blabbering away, putting ideas out there. Yes, if we don't test the flat breech, what's the point of all this testing?

Look at the bottom of my last post, where I talk about two different barrels. I think this is the way we are going to have to go. Two barrels. The flat breech will require a touchhole IN the barrel itself, which will make it unsuitable for using on the Nock breech.

That's how I think it will have to go. Two different barrels, each one trimmed to the same loaded length.

Has anyone heard of the Nock breech being unsafe, since it has the small antechamber, which could have high initial pressure. Comments and suggestions welcome. Also note that the drawing I have done is just a sketch, the proportions and dimensions need to be defined and refined.

Never heard they were unsafe; but my impression is that the design of the Nock is such that it is a great fouling trap and prone to misfires for that reason! Course better answer should come from a shooter of one such!

[Acer Saccharum]

The Nock is designed for a certain kind of shooting.

I think it would be a miserable breech for you if you wet clean between shots. I like to shoot without cleaning between shots. If the fouling starts to crust up, I use a blowtube to add some moisture to the bore. I think the Nock would work for me at the range.

But if I were in the field with a deer rifle, I would much rather have a plain breech, where simplicity of cleaning is guaranteed.

[Benedict]

The Nock is designed for a certain kind of shooting.

I think it would be a miserable breech for you if you wet clean between shots. I like to shoot without cleaning between shots. If the fouling starts to crust up, I use a blowtube to add some moisture to the bore. I think the Nock would work for me at the range.

But if I were in the field with a deer rifle, I would much rather have a plain breech, where simplicity of cleaning is guaranteed.

On the other hand if the Nock were more reliable, quicker and more powerful wouldn't you want it in a deer rifle?

Bruce

[rich pierce]

It will be an interesting experiment but I suspect that many will stick with the type of breech most commonly found on originals of the same sort.

[David Price]

I will be surprised if there is any appreciable difference if both barrels are clean.  If they are both very dirty may be the flat breech will be quicker.  In either case not enough difference for a human to detect.  There goes my common sense kicking in again.

[Larry Pletcher]

I will be surprised if there is any appreciable difference if both barrels are clean.  If they are both very dirty may be the flat breech will be quicker.  In either case not enough difference for a human to detect.  There goes my common sense kicking in again.

Hi David,
I think you are very likely correct.  I hope my ability to avoid variables is good enough to show differences.  But, in any work like this I have to be willing to admit the findings could be inconclusive. 

If someone pinned me down for a speculation, it would probably be that the faster breech system will be the one that places the barrel charge and the priming powder the closest to each other.  It may be hard to beat a plain breech with a vent liner with a very thin web and priming powder up against the barrel.  On the other hand a Nock breech may get prime and barrel charge together just fine.   I guess the point of the test is to fine out. 

With the various tests I've done there are a few things that I'm beginning like:
fast locks
Swiss Null B priming powder
Chambers vent holes
Vent dia in the .064-.070 range
very slight exterior cone on liner
prime against the barrel

Now I have to think about breech design - never even considered that before.  This should be fun.  I thank you all for the chance to bounce ideas around.  We have a chance to actually put numbers on things that we have only guessed at before.

Here's a question for your thoughts: you are shooting birds in 1800-1810 with a state-of-the-art English double fowler.  Do you think you could sense an extra fast breech by the amount of lead you use to get on the bird?  Can you today shooting clay pigeons?  Or are there too many inherent variables in a flint ignition system to sense a change in lead?

Regards,
Pletch

[Acer Saccharum]

On the other hand if the Nock were more reliable, quicker and more powerful wouldn't you want it in a deer rifle?

Bruce

Absolutely, if it's the best breech. How do we know except to run this experiment.
I just think the Nock would be great under certain conditions, and more likely to be finicky under others. The good old reliable flat breech would be hard to beat.

[rich pierce]

Any chance a longer barrel would better reveal any advantage of one breech over another?