Is excess powder really blown out?

[Carbon 6]

PV=nRT
https://en.wikipedia.org/wiki/Ideal_gas_law

Where are you going ?

 

[zimmerstutzen]

There is a point for many guns at which proportionately more black powder does not produce proportionately more velocity. This is easily chartable in 45 and 50 caliber guns. Velocity may still increase but usually at much reduced increments. A portion of charges over that amount tend to be burned up in muzzle flash. Now whether the "spew" therefrom is unburned or just soot has also been a much debated question. Many years ago, shooting a short barrel rifle (IIRC 23 inches) a buddy and I intentionally fired many heavy charges over a large piece of cardboard. When we did our experiment we intentionally used 1 fg. What was collected on the cardboard was mostly ash and cinder type material, but there was a small amount of what appeared to be unburned powder grains. The couple table spoons of detritus we collected from the cardboard burned slowly when lit with a match. Perhaps 7 or 8 times slower than putting a match to a tablespoon of unburned powder and certainly without the whoosh. Regardless I certainly would not want to hold that in my hand and light it. as a side note, when a significant amount of real black powder is still burning when the ball exits the muzzle, fouling tends to be much heavier. There is a huge debate over whether that point in the powder charges is most efficient, etc. It is from one view, but not necessarily for a hunter who wants a flatter trajectory, or who is trying to extend his range by 15 yards. Most target shooters find that their most accurate loads are about 75% of that point where velocity gains start to wane. But they already have guns more suited to target shooting and do not want to shoot several relays with bruises and fatigue from heavy charges. Once the bore gets to 54 and larger, the point where velocity increases are not as high, seems to disappear.

For instance, I have a 75 caliber very heavy barreled pistol. It was specially made for blank shooting. I can shoot 200 grains of powder under 2 shotgun wads and the muzzle flash is still minimal In my 45 caliber kentucky pistol any load over 40 grains has a huge muzzle flash. I suspect there is something about the larger bore diameter which permits faster burning of the powder within the barrel.

 

[Black Hand]

Where are you going ?

Just showing the relationship between Pressure, Volume and Temperature...one variable does not change without affecting the others in some way.

 

[jrdavis]

The presence of unburnt powder could be easily determined. Shoot over a sheet, collect the ejecta and try to set it a-light. Unburnt powder should flash and carbon won't really do too much...

see post #5

 

[Black Hand]

see post #5

Then why does this discussion continue and keep coming back like a Herpes virus...?

 

[Carbon 6]

Just showing the relationship between Pressure, Volume and Temperature...one variable does not change without affecting the others in some way.

Ok, I thought maybe you had an argument.
I would add that we are producing gas and heat also affects the rate of production.

 

[Carbon 6]

see post #5

https://www.muzzleloadingforum.com/threads/is-excess-powder-really-blown-out.112256/#post-1527037

Some folks look to the east and see the sun rise and are content , others wonder why it does ?

 

[Black Hand]

Ok, I thought maybe you had an argument.
I would add that we are producing gas and heat also affects the rate of production.

In other words, all the arm-chair physics-ing by people unfamiliar with the science is little more than wheel-spinning...

 

[Carbon 6]

Considering that BP makes a great fertilizer, The ground 20 feet in front of the shooting line at the range should be quite green with grass if unburnt powder where being ejected. This I have not seen.

 

[Carbon 6]

In other words, all the arm-chair physics-ing by people unfamiliar with the science is little more than wheel-spinning...

I wouldn't word it like that, people learn in different ways. Sometimes it's a fun process, sometimes it's messy. The point is to question, learn, test, observe and repeat.

 

[Britsmoothy]

Where are you going ?

Down the pub

 

[Carbon 6]

Down the pub

Wait, I'll go with you.

 

[Black Hand]

I wouldn't word it like that, people learn in different ways. Sometimes it's a fun process, sometimes it's messy. The point is to question, learn, test, observe and repeat.

I agree. But too many just want to argue and ignore the available evidence.

 

[tenngun]

I note on pressure test that the breach pressures go up with each increase in charge, even when velocities don’t move or go down. I also note what looks like unburned powder can be seen with even light charges.
Even a charge that produces 1100 FPS at the muzzle means that in a 42” barrel the ball and charge are only in the barrel about 7/1100 of a second. Is that enough time for fire to move through even a small column of powder??? Beats me, but I have found that big charges don’t pay off down range.

 

[necchi]

Since velocity is directly proportional to the pressure, how is that possible?

Because it's not a linear curve?
It's a matter of time and distance.
The ball (a mass) travels the barrel from point A (seated position) to point B (the muzzle) from 0-velocity to it's velocity at exit.
Hypothetical figures here;
The mass is pushed say 28"'s by 10,000 psi to attain velocity X,,
If you increase to 20,000 psi the mass is pushed that 28"s faster,,
We all get that.
But that mass still has to travel that 28"s. It takes time to move that mass 28"s
At some point as the pressure increases,, the time the mass needs to move 28's is still the same.
The increased pressure can't move the mass from 0 velocity 28"s any faster as a matter of acceleration vrs the time it takes to travel.
The excess pressure blows the barrel.
For the mass (the ball) to travel at a higher velocity it needs to be pushed longer and harder by the pressure.
They tried that,, the barrel still explodes.
Pressure is released energy. And BP expends all it's energy at once.
For velocity to continue to climb,, the energy has to increase with the time traveled. Not expended in an instant like exploding powder.
Like a rocket ship leaving earth.
It's the physics of acceleration and time. I'm not a good explainer.
If velocity increased linear to pressure we could send a ball to the moon. For the ball to move faster, we'd have to set off a second pressure release behind to push it as it attains maximum velocity from the first pressure release.
It takes time to move the mass to velocity X, then more time to move it to X+

 

[George]

Pressure is increased by both production and by heating of those gasses.

If you could burn a charge of BP but keep the temperature from increasing, it would expand to 280 times the volume of the charge. But, if you heat that original gas to the burning temperature of BP, 3880F, then it would expand to 3600 times the volume of the charge.

Spence

 

[George]

Robins calculated that the maximum velocity of any ball shot from a smooth barrel, musket or cannon, required a charge of powder 1/2.72 of the length of the bore. After that whopping charge, any additional powder resulted in velocity less than maximum.

Spence

 

[longcruise]

Paul V claimed to have gathered unburned powder and ignited it. I always took him with a grain of salt.

 

[Black Hand]

Paul V claimed to have gathered unburned powder and ignited it. I always took him with a grain of salt.

He was rather wordy and after the 8th paragraph, I stopped reading (OK, much before the 8th). As a lawyer, he had a way of using 100,000 words when 10 or less would do...

All that said, it would be easy to test.

 

[George]

No one bit on my question as to what exactly was meant by 'excess' powder, but it's pretty much the reason behind this long-running discussion about unburnt powder being blown out of the bore. In the 18th century and I don't know how much earlier, the belief was that for every barrel length there was an exactly perfect amount of powder in the charge. If the perfect charge was used for that length barrel, then the powder would be completely burned exactly when the ball reached the muzzle. Any less than that amount and all the powder would burn, but some power would be lost. More than the perfect charge and it could not all be burned in that length barrel, and so the 'excess' would be blown out and wasted.

Experiments and better understanding proved that idea to be incorrect, but it has hung on to the present day, maybe just to give us something to talk/argue about.

Spence