Unburnt powder

[paulvallandigham]

Yes. About 30 years ago, now- perhaps more-- The President of my local club and I did the test, shooting over a clean, white bed sheet. We tested Goex 3Fg loads in several rifles.

After each shot we collected the powder off the sheet, and put it in an alum ashtray we kept at the club range for our scorekeepers to use. We obviously wiped out the ashtray before we began. Some of the grains of powder looked brown rather than black in color, and NEITHER of us thought the small pile would really burn. Ray touched the pile with the lit end of his cigarette, and we both jumped back when the powder ignited. We laughed!

As I said, and have said here before, Neither of us was expecting UN-burned powder to be on the sheet. We shot off a bench rest, so that the sheet was only about 36-42" below the muzzle when the guns were fired. We tried different loads, finally working back down to where no unburned powder was on the sheet. We then tried several shots of those powder charges to see what kind of accuracy we got.

I know I was testing my .50 cal. Tenn. Poor Boy style rifle with its 39" barrel. Ray had a couple of guns, but I believe most of his testing was with his .45 long rifle. The barrel was either 42"" Or 44" Long. I No longer recall the powder charges we tried, as we did not keep records that day. We went solely to test this idea that with enough of a powder charge, some powder would leave the muzzle unburned.

Consider the simplicity of the test, it takes a very layed-back sort of person not to do it himself, no? BTW, The rest of our club members were shocked to find out that we got unburned powder when we announced out results. Like us, they also thought this was just an old wives tale. After all, we had all seen burning powder in front of the muzzle-- how could any escape?

I hope this information helps all you non-believers sleep better tonight. :wink: :v :hatsoff:

 

[cynthialee]

Conviced me.

I just figured it was ash and crud that came out after the bullet.

Do pistols also leave unburned powder?

 

[Dphar]

I shot a 32 percussion with a 32" barrel over a sheet and got up to 65 gr vol of FFF with no powder on the sheet.
I gave up at that point. This was in a building BTW so there was no place for the unburned powder to go.
There should have been SOME on the sheet.
Unless it was overshooting the sheet a getting smashed against the wall.
If I though it meant anything I might test it. But then look at the charges some of the BR shooters use with a RB. I shoot 109 from my heavy 50 cal and may try 120 if the weather ever lets me shoot. Too dry here, fires all over the place....
But its not California so it don't make the news...

Dan

 

[Dphar]

Really makes one wonder how the patch can be burned to a toasted bread brown by 3000 degree powder gases and there be unburned powder behind it.
This said, experience has shown that almost anything is possible.
Dan

 

[Rifleman1776]

I think we should have a forum here just for some of these 'never ending threads'. :stir:

 

[Vaino]

Hi Dan...I do think at some powder charge, unburnt powder granules will be evident. To exaggerate a bit...if the bbl were filled completely w/ powder, there definitely would be unburnt granules on a sheet. So now lets only fill the bbl half way....I think there will be unburnt granules on the sheet. If we started to load high end powder charges and then went up from there, I'm convinced at some increased charge, unburnt powder granules will be evident on a sheet.

In fact it would be an interesting experiment if we loaded a bbl half way w/ powder.... would the pressure peak be reached and the remainder of the unburnt powder be expelled from the bbl? This then would be self regulating pressure or a safety valve? A large outside dia. bbl could perform this test and if a "crusher" pressure setup were installed, I'll bet that the pressure wouldn't be as high as expected. Just thinking out loud.....Fred

 

[Robert Egler]

Umm... YOU try that experiment first and let me know how it turns out. :v :haha:

 

[longcruise]

From "An Essay on Shooting", Wm. Cleator, 1789, in a discussion of the mistaken reasons for long barrels:

Spence, thanks for posting some very interesting info. :thumbsup:

I think the Royal Society may have overlooked one thing, and that is that even though all the powder might be consumed in a short barrel, a longer barrel still seems to provide more velocity. IMO, the ball continues to accelerate down the bore till it exits. Of course, an extremely long barrel could probably begin to show deceleration as is the case in some very long barreled .22 rimfires.

 

[JohnTulle]

When I switched to using a spit patch, I noticed the spent patches had a ring of what looked like unburned powder on them. Even more curious was that some of the grains had shades of red and brown. Has anyone else experienced this?

Sorry, no pics.

John

 

[zimmerstutzen]

There are arguments and theories both ways that seem to make sense. However, the night photograph means absolutely nothing. All you see is the burning and glowing particles. If any unburned granules fell, there would be no way to see them.

Even the old advice may be wrong in calling the residue powder. Certainly there are solid soot particles. The question is whether there are also unburned grains. I have seen unburned grains in amongst the soot on a piece of oil cloth. We only did two such shots. if there is, might it only happen with 2 fg? or with such heavy loads that such are shoulder jarring suicidal charges that no sane person would do it?

 

[Larry Pletcher]

Zimm...,
I have a photo showing a piece of burning charcoal that is casting a shadow on the ball. The charcoal apparently is traveling faster than the ball. I offer this to prove nothing. I just thought is was cool and interesting.
Regards,
Pletch

 

[jim gray]

I've never tried to recover unburned powder after shooting, but I've seen residue on the bench that could have been either powder or soot left from shooting. As many other posters say, I don't really care if I waste a grain or two of powder if the ball goes where I want it to.

For recommended starting loads, the charts in the back of a DGW catalog work well for me.

 

[George]

I think the Royal Society may have overlooked one thing, and that is that even though all the powder might be consumed in a short barrel, a longer barrel still seems to provide more velocity.

I won't be first in line to question the Royal Society, even though they were working much closer to the beginning of our understanding of ballistics than we are. The old boys didn't always get the numbers right, but they got the principle right an amazing percentage of the time.

Everyone always seems to assume that when the powder stops burning the acceleration stops. Think about this little hypothetical scenario... what if all the powder is burned before the ball has begun to move. Black powder produces a large volume of gas, so the volume which was occupied by the solid powder is now occupied by all that gas. Very strongly compressed gas. It begins to push the ball up the bore, and as the ball moves, the space behind it increases. The gas expands to fill that space, so the volume occupied by the gas increases. It continues to increase as long as the ball is moving up the barrel. Now the same volume of gas is occupying a much larger space, so the pressure drops. But... the volume of gas produced is many times greater than the volume of the whole bore, so even when the ball is at the muzzle, the pressure behind it is still very high. As long as the pressure is high, the ball continues to accelerate. Once the ball exits the muzzle, the pressure drops to zero, acceleration stops. So, it is totally logical that a longer barrel will allow acceleration over a longer time period and achieve a higher muzzle velocity. The same volume of gas in a very short barrel will not have as much time to accelerate the ball, even though the pressure starts out the same.

That's the reason short barrels generally yield lower muzzle velocities. It's because time available for acceleration is limited, not that there wasn't enough barrel to allow all the powder to burn. I think the old boys had it exactly right. The powder all burns extremely quickly, long barrel or short, and the concept we've all heard of for so long, that the proper amount of powder must be found for each barrel length so it will all burn up, and any excess is blown out the muzzle unburned is completely wrong.

Another way of looking at it is that you have created an air gun which you don't have to pump. And it smells better. :haha:

Spence

 

[zimmerstutzen]

I think your right about the pressure continuing behind the ball in the longer barrel. (Except when the charge is so low that the longer barrel produces lower velocities.) Has anyone actually confirmed that the powder is all burned. For instance, when the ball over a given charge exits a 26 inch barrel the peak pressure is "x" If your theory is correct that the powder is burned before exit, then the peak pressure would still be the same for a longer barrel. And that would be true for a whole range of powder charges, that the peak pressures would be the same regardless of barrel length for each charge. If on the other hand, there are peak pressures that are higher for a longer barrel, then obviously that charge is not completely burned in the shorter barrel. I suspect that there are: (1) low charges for which the peak is the same, but the velocity of the longer barrel is less (2) moderate charges for which the peaks are the same but the velocity in the longer barrel is higher and (3) larger charges for which the peak pressures are higher for the longer barrel evidencing that the powder is still burning at muzzle exit.

If the powder is all burned before powder exit, why do we reach a point with short barrels in which higher charges yield only very slight or even no velocity increases? To me this last point is proof that there is a point at which charges are not consumed within the barrel. As it happens, these charges tend to be beyond what most shooters use anyway.

 

[hanshi]

I'll go out on a limb and say no unburned powder makes it very far, if at all, out of the muzzle. It simply makes a bigger flash in front of the muzzle. A longer barrel allows the partially combusted gases to continue to burn in the bore giving higher (generally) velocities. Peak pressure is attained in the first few inches of the barrel. Look at it this way; put anything in front of the muzzle and fire and it will be set on fire. If clothing will catch fire it's a no-brainer as to what happens to touchy black powder. Just my analysis and not to be taken as absolute fact, which you may take it as fact if you so desire. It may be fact; who knows? Heck, I don't know; just skip this post unless, of course, you're bored and just looking for something to read. In that case read it and cogitate a while. Me? Well I'll just go have a drink or watch tv or something. And mayb.... :dead:.....Hanshi, SHUT UP! Uh, gotta go folks.

 

[Rifleman1776]

As long as the pressure is high, the ball continues to accelerate. Once the ball exits the muzzle, the pressure drops to zero, acceleration stops. So, it is totally logical that a longer barrel will allow acceleration over a longer time period and achieve a higher muzzle velocity.

Well....only, kinda, sorta.
More accurately, as long as the pressure is high enough will the ball continue to accelerate. The matter of friction can affect velocity. Longer is better only up to a point then it becomes a matter of diminishing returns.
But, really the point is: so what? Wat works, works.

 

[Larry Pletcher]

Well....only, kinda, sorta.
More accurately, as long as the pressure is high enough will the ball continue to accelerate. . ..

I agree. Mann shows photos of bullets that expand the base outside of the muzzle. Expansion is too great to occur in the bore. If the pressure is great enough to expand the base in front of the muzzle, there is enough pressure to increase velocity.
Regards,
Pletch

 

[Rifleman1776]

You did say

If

.
Comon' lets keep nit picking each others words. :stir:
Who knows, it could get fun. :grin: :surrender: