The inefficiences of Flintlocks

[Redstick Lee]

Yes, gas escapes from the vent but I do not believe it has any significant effect on pressures and thus velocity.

How would you know? PLEASE again, don't take that as criticism. One cannot test such things very accurately unless one has barrel pressure test equipment. Further, we don't even try to test such things normally. Most of us normally find the best ball size, patch type/thickness/lubricant and the best grain size and type of powder for the most accurate load and we go with that. As long as the vent in a flintlock is large enough to function properly, that's the sum total most of us do.

Can't help but recall the DGW catalog add where they tested a section of one of their barrels by installing breech plugs at both ends drilling a vent, filling with powder and lighting by a fuse.....They claimed all the gas came out that vent....without the barrel exploding.
I don't think they would have had the same results had a bolster and nipple or patent breech been installed, and fired by percussion cap.

IIRC that was 1973........I still have that catalog here somewhere...i'll look for it tonight

 

[Gene L]

I seem to recall a closeup of a BP rifle at the muzzle in slo-mo. There was definitely blow by that preceded the ball. I don't know if it was a flint and can't find the video, but it struck me at the time. A round ball has a very small contact area of the ball on the barrel, so I was not totally surprised that powder burning velocity blew past the very small (relative to the bore) and a cloth patch.

 

[coloradoclyde]

I seem to recall a closeup of a BP rifle at the muzzle in slo-mo. There was definitely blow by that preceded the ball.

You don't have enough information to make an assessment. You don't know how or what the gun was loaded with. All you can do is make assumptions about assumptions.

 

[tenngun]

Slo-mo of modern guns show a gas coming out before the bullet. Blow by or compressed air :idunno: or a little of both. Apatch often shows a cross shaped light brown area that I always took to be blow by.

 

[nkbj]

I seem to recall a closeup of a BP rifle at the muzzle in slo-mo. There was definitely blow by that preceded the ball. I don't know if it was a flint and can't find the video, but it struck me at the time. A round ball has a very small contact area of the ball on the barrel, so I was not totally surprised that powder burning velocity blew past the very small (relative to the bore) and a cloth patch.

Are you thinking about an old copy of a Lymans black powder manual, discussion, diagrams and photo being the loading of patched round ball and how to choose ball diameter and patch thicknesses?

 

[coloradoclyde]

If the gun has a coned barrel, I suspect any photo will show blow-by....

 

[smo]

To me there would be more blow by with a conical lead bullet than with a parched round ball considering the ball has the correct thickness patch vs no patch.

The brown area on spent patches I always associated with the flash of the powder on the back side of the patch.

Holes in spent patches I associated rifling on newer barrels cutting the patch or insufficient lube or dry , or old patching material. :idunno:

 

[Gene L]

I seem to recall a closeup of a BP rifle at the muzzle in slo-mo. There was definitely blow by that preceded the ball. I don't know if it was a flint and can't find the video, but it struck me at the time. A round ball has a very small contact area of the ball on the barrel, so I was not totally surprised that powder burning velocity blew past the very small (relative to the bore) and a cloth patch.

Are you thinking about an old copy of a Lymans black powder manual, discussion, diagrams and photo being the loading of patched round ball and how to choose ball diameter and patch thicknesses?

No, I think it was on TV, but simply can't remember or I'd pull it up. It could have been a smoothbore. Super slo-mo. I'll keep looking for it and if I can remember more, I'll try to share it.

 

[Vaino]

As I said before.....002-.004 0f compressed patch mat'l in the grooves will not resist the force of the gas generated by 8,000-10,000 PSI.

The patch mat'l's contact in the grooves is tangental and actually would be quite short in length.

So...a tight PRB combo that can still be loaded using a short starter and RR will allow some blowby....and judging from some of the easy loading PRB combos that some members shoot.....a lot of blowby occurs.

Some don't realize just what 8,000-10,000 psi can do.......Fred

 

[Larry Pletcher]

This is probably not the video you are thinking of, but it is one we did in my garage years ago. It was done at 15,000 fps and you can see gases, the ball and the patch separating from the ball.

slo mo rifle

I also have some stills of the patch separating from the ball. One of those shows a bare ball with the shadow of a spark on it. (Think about that a minute.) The still with the spark shadow is somewhere in the middle of the article. The best stills are at the end. We had many failures before figuring it out.

patch separating from ball

Regards,
Pletch

 

[nhmoose]

If I was worried about inefficiency's I would never use a Muzzle loader of any style.

That is the truth and why Would anyone but us who like a challenge.

 

[thomas]

Well said!

 

[tenngun]

:thumbsup:

 

[Larry Pletcher]

If I was worried about inefficiency's I would never use a Muzzle loader of any style.

That is the truth and why Would anyone but us who like a challenge.

I agree. There is no firearm type that hold my interest like a properly functioning flintlock.
Regards,
Pletch

 

[Vaino]

I won't defend the use of a MLer that shoots PRBs...no need to. This topic isn't a criticism of using a PRB, just pointing out some drawbacks. I only build flinters and also hunt w/ them along w/ my caplocks ....all of them use PRBs.....Fred

 

[Rifleman1776]

On the slo mo, I couldn't pick up any blow-by. Maybe I missed it, watched several times. But, methinks, what some call blow-by is nothing more than compressed air from the bore ahead of the ball being blown out. As someone pointed out, this effect can also be seen with modern rifles. Not saying a loose fit ball/patch will never have blow-by. But, methinks, a properly fit ball/patch combo will seal the exploding gasses.

 

[Irish lad]

I sure learned a lot reading this thread!
Thanks,
Irish

 

[coloradoclyde]

On the slo mo, I couldn't pick up any blow-by. Maybe I missed it, watched several times. But, methinks, what some call blow-by is nothing more than compressed air from the bore ahead of the ball being blown out. As someone pointed out, this effect can also be seen with modern rifles. Not saying a loose fit ball/patch will never have blow-by. But, methinks, a properly fit ball/patch combo will seal the exploding gasses.

I agree.....I also think that a patched ball only needs to resist the pressure for a fraction of a microsecond. once the ball is moving the pressure on it is greatly reduced.

Lube that was smeared all over the bore when the ball was seated, acts as additional sealant as the ball travels down the barrel.... Or at least it's a possibility..... :hmm:

 

[Artificer]

On the slo mo, I couldn't pick up any blow-by. Maybe I missed it, watched several times. But, methinks, what some call blow-by is nothing more than compressed air from the bore ahead of the ball being blown out. As someone pointed out, this effect can also be seen with modern rifles. Not saying a loose fit ball/patch will never have blow-by. But, methinks, a properly fit ball/patch combo will seal the exploding gasses.

I spent a career building and re-building NM and other target rifles and pistols and have watched more Slo Mo videos on the bullets exiting the muzzle than I can remember to count. I have seen others on ML PRB's that Pletch and others have done.

Special :thumbsup: :hatsoff: to Pletch for sharing the results of all the testing he has done over the years!!

Yes, there is always some "compressed" air that exits out of modern and ML's guns before the projectile comes out. I don't know the technical name for that compressed air, so I hope the real mechanical engineers will excuse that.

Some of the tiny bits of "ejecta" that come out of the bore of a ML are burnt powder residue. Tiny burning bits of ejecta or sparks in the air or on the patch as it exits the bore- are actually grains or pieces of grains of powder that did not and would not have burnt in the bore, because there was not enough potassium nitrate close to the unburnt bits while still in the bore. This because each grain of black powder cannot be a perfect ratio mix of charcoal, Sulphur and potassium nitrate. (Potassium nitrate is what supplies the oxygen for burning powder in the bore after the oxygen in the air inside the barrel is quickly burnt up.)

Once those tiny bits of powder that would not have burnt in the barrel (because they did not have enough potassium nitrate) are exposed to the atmosphere after the PRB has cleared the muzzle, then there is plenty of oxygen in the atmosphere to allow them to burn as long as the tiny bits are still hot enough from the super heated gas exiting the muzzle. Of course not all the tiny bits will burn once they exit the muzzle because the super heated gas disperses/cools as it exits the muzzle and therefore doesn't provide a high enough temperature for all the tiny bits of ejecta to ignite.

Sorry to go "into the weeds" a bit about tiny bits of ejecta that will or will not burn once they exit the muzzle and hit the atmosphere, but when many people watch Slo Mo videos of balls existing muzzles, they are naturally attracted to these bits of ejecta and sort of lose the gas coming out of the muzzle.

Modern projectiles in modern barrels make it easier to see the gas exiting the bore when the projectile clears the muzzle, because there is no patch nor usually not as many types of ejecta to distract eyesight. Modern projectiles usually seal the bore better as well, because the projectiles are oversize when they hit the rifling and "crush down" mechanically to better fit the rifling grooves, though it is not a perfect seal of the gas behind the projectile.

PRB's cannot be as perfect of a gas seal found with modern projectiles, because they are not oversize when the patch/ball hits the rifling. Patch lubrication and lubrication in the barrel are not dense and resistant enough to form a seal in the barrel. Any lubrication that is not burnt up in the barrel, is also ejected from the muzzle.

It can be very difficult for the human eye to pick up the gas as it escapes around the PRB, when the PRB exits the muzzle, even with excellent and extremely high speed photography. However, because the PRB cannot form even as good of a gas seal as a modern projectile, the gas will not exit the bore uniformly.

Gus

 

[coloradoclyde]

Here ya go guys, The cap and ball youtube channel put out a slow motion video....

https://youtu.be/dsuYy8kTcYQ