On another thread it was discussed about whether all powder is burned in the first few inches of the barrel. It was written about by John Barsness, a writer I enjoy, in Handloader. It is not an exact quote. Do you agree or disagree with this statement :

"All the powder from a properly loaded modern smokeless cartridge will be burned within the first several inches of barrel"

I hate to answer a question with a question but would "A properly loaded modern smokeless cartridge" include something like a modern 45-70 loading?

Some reading I've done, perhaps one of my reloading manuals, says that one of the ballistic factors taken into account in high level physics analysis of loads is the weight and velocity of combusting propellant as it proceeds down bbl.

If it all burned in the first inches, wouldn't that suggest loss of pressure before the projectile left the bbl?

Gatehouse,
If it all burned in the first two inches or so, how do we get muzzle flash. It is burning gases or flames from it. If it is all burned we would just have smoke. I would have to disagree, and like you, I enjoy his writing.

Burning all of the powder in the first few inches of bbl would also suggest that you could cut a bbl down to the end of that first few inches and experience NO velocity loss or perhaps even a velocity gain from the now missing friction. I don't think so.

JohnTheGreek

Nope, I can't agree with that statement either. I think that Barness states that muzzle flash is caused by "oxygen burning" or something like that...again I dissagree. If there were any truth in his statements our (& the powder companies) whole understanding of "slow" and "fast" powders would be incorrect as would our understanding of the relationship between barrel length and velocity.

I think we are over-looking something. It's not where the powder is burned but what is taking place down the REST of the barrel length is the EXPANDING GAS. In my little mind, this constant expansion is what is accellerating and pushing the bullet ever faster and faster...NOT the physical burning of the powder.

If all the experts and whiz kids that study this stuff say it BURNS in about the first 3 inches of the barrel, OK. I'll buy that. Anyway, I think the "expanding gas" is the bouncing ball we need to watch. Probably this burning powder is why it's the throat that gets burned out of rifles first. NO? Just my feeble opinion on a subject I sure don't claim to be an expert on.

I disagree, as long as "several inches" does not mean 22 or 24 inches.
montero

Pecos,

Barns is the only person I have seen who makes that claim in a publication; as far as I know his views are not supported by any of the experts from any of the powder manufacturors....If someone can produce evidence from any of the powder manufacturors which supports Barns I would very interested in seeing it...

My own "theory" is that there is only so much oxygen available to burn sealed behind the bullet in the barrel and that hinders complete combustion once a certain amount of powder has been burned. Once the very hot gass plus un burned powder exit the barrel it comes into contact with more oxygen and hence ingites and we have muzzle flash.

I have no idea how accurate this is as for all i know powders may contain their own oxidizers,
its just a stab in the dark on my behalf!

Regards,

Pete

Pete - Gunpowder produces it's own oxy for combustion. It's like a solid fuel rocket.

Where I got the information about WHERE the powder was burned was from my program ACCULOAD.
It will calculate this distance for you. Now, where did the guys at Accuload get the info? I believe from the powder manufacturers. I know they get a lot of technical info from them.

I was previously like all the rest of you and believed powder was this big boiling, burning blob of stuff racing down the barrel. But the more research I've done on it, the LESS I'm inclided to believe this any more. I think the only thing racing down the barrel is hot expanding gas and various residues...possibly a very few unburned flakes of powder in some instances. I think the muzzle flash is nothing more than the release of the fire that took place a long way back down the barrel.

This is a good point to stop and ask Hockeypuck of AEM Inc. and Accuload where they got their information about powder burn. All I know is that I have run the numbers in their program and come out with the same thing Barness is trying to say. I ran the numbers several times, in fact, thinking I made a mistake.

I'll email Hockeypuck and ask him to respond on this thread.

Pecos,

Thanks for the info...I have not seen the chemical formula for a modern powder but suspected the inclusion of a oxidizer was a distinct possibility.

I have not played with Accuload myself but it is certainly well respected in reloading circles. So where does this notion of burn rates and fast and slow powders come from? Are we in fact talking about fast and slow rates of expansion of gas produced??? Would love to see a technical description of what is actually going on here.

I am still not entirely convinced, but data from Accuload would certainly go along way in selling me the idea....

regards,

Pete

In one of Keiths books he relates powder does not all burn in the barrel. If I remember correctly he worked at an arrsenal in Utah during WWII and was proofing .50 cal. machine gun barrels. Said at the end of the day that there was pounds of un burnt powder in front of the bench. But you know Keith...but still enjoy his writings.
As a sidenote...
Ever shot a .22 rifle off the bench in the winter with snow on the ground?
Lots of black stuff in front of the muzzle on the snow.
My quess is that is burnt powder.
FWIW

After reading the Barsness comments, I called one of the techs at Hodgdon. He said that they often find unburned granules of powder all along the bore, even at the muzzle.

Another thing to consider is the "bed sheet" test, which is used to actually see if all of the powder in a particular load is burning. You lay a white bedsheet on the ground a few feet ahead of the muzzle and fire a shot. If you have a load that is considered "overbore," meaning that you're using more powder than can be burned in that barrel, you'll see unburned powder grains on the sheet.

The question is why did these grains not burn? What "saved" them from the advancing flame of the rest of the charge? It would seem that in these cases, powder is in fact burning the entire length of the barrel, and when the burning charge exits the muzzle and the powder granules hit the cool air, they disperse and fail to burn.

Another thing to consider: In handguns, the 357 Magnum 125 grain JHP has a huge muzzle flash due to the powder charge necessary to get that bullet to the high velocity it enjoys from handgun barrels. Police departments and personal defense experts asked the industry for a different recipe which did not cause such a flash, which can blind the shooter in dark environments. The industry responded with quicker powders designed to burn up before the bullet exited the muzzle, thereby eliminating the flash. This too seems to indicate that some powders burn all along the barrel's length, and continue to burn after they exit the muzzle.

I think if you take Barsness' comment to mean that most of the powder charge burns in the first 5 or 6 inches of barrel, that's probably a fair statement.

I do think that Pecos is right about the expanding gas being what pushes the bullet along, even after the powder charge is burned. Think about a couple of pinches of Unique in a 30-06 case. The bullet will exit the muzzle, but the Unique has probably all burned (100% relative quickness) before the bullet enters the throat.

Barsness has probably misspoken. He should have said "most" instead of "all," it would seem. I'm generally pretty cautious of what he writes, as I've found significant errors in his words in the past.

Dan Newberry
green 788

I am certainly not knowegeable enough to comment on the technical aspects of this but one experience I had may shed some light on the subject. When I was working in Iran powder was very difficult to get for my 270 and loaded ammo impossible. So when I made a range sweep I picked up unfired 20 mm rounds from the Cobra live fire training and salvaged the powder. I worked up a load using light bullets (110 gr I think) which we used just for plinking, rabbits at night, etc. The load turned out to be a full case of powder and the bullet was still eight inches low at 100 yds with the rifle sighted in for 130 gr loads. The first time one of my boys shot a rabbit at night with the spotlight the muzzle flash blinded us. Obviously the powder was so slow burning that it didn't all burn in the bbl. The bbl on the 20 mm was 50 inches long. Playing with this load in the desert we could find unburned powder in front of our firing position. Of course all this took place when I was young and stupid.

Does that mean that you could reduce the powder charge by the amount you find and still get the same velocity? I don't know.

Guys, we have all seem flaming particles come out the barrel and the only explanation is this stuff has got to be unburned/burning powder. I don't know for sure exactly where any of the stuff really burns. I just read a post on another forum where Ed of Accuload was commenting on powder data and he was lamenting that powder manufacturers are a secrative lot as a whole.

And I don't doubt that with some of the big guns like 50BMG, 20mm etc. that there would be some unburned grains of powder blowing out the front end. I have certainly seen unburned grains of slow burning powders in the action and magazine etc when firing certain reduced loads.

For sure there is such a thing as unburned powder but I think the idea is to get it to pretty well do it's trick mighty fast and let the expanding gas (which can't go but one way) do the rest.

If the powder had to burn all along the barrel and in effect build up a "head of steam" I think we would ge a very different resulting "lag time" from when you fired and the bullet actually got its butt moving and out the barrel.

Hopefully some of the guys who KNOW the answers here will come along and keep us from making any more wild guesses.

Speaking of which, I once heard that BALL powders tended to burn out the barrel at about "mid-point" rather than take out the throat. Anyone ever heard such a thing. In fact, this phenomenon was supposedly why ball powders were selected by the military, i.e. longer barrel life.
Again just repeating hearsay.

Try this, roll up some printer paper & tape it to your muzzle. It leaves a definite powder streak. I don't know if it is residual powder or powder residue that is along for the ride.

I have examined bodies of people that have been shot at closer ranges and found powder imbedded in the skin around the bullet hole along with powder burns..

I have cleaned bits of powder, mostly slow burning powders, out of my barrels.

I have shot over a sheet and found unburned powder.

I have also found some unburned powder in cases after firing...

I believe there is just too many varibles in this equation for Barsness to make such a flat statment.....Probably a writters handycap, we may be misinterpeting his meaning altogether or he may have made a slight bobo, it happens.

Ray, no doubt there is some particulate matter which sure looks like gunpowder, although most of it I've seen is considerably discolored. My question here would be IS this "particulate matter" really a useable form of gunpowder or perhaps something akin to garbage that is in all powders to a small extent.

I am not trying to cling to the theory that dogmatically states the stuff burns in the first 3-5" inches of the barrel as I really have no horse in this race. But now that the issue has been raised, I wish some techy person really in the know would comment on this question and enlighten all of us. My interest is piqued and I'd like for us to leave no stone unturned. Good hunting to all and may all your powder burn cleanly!

[ 11-06-2002, 01:28: Message edited by: Pecos45 ]

Di Maio, Vincent J.M. Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensic Techniques. Boca Raton, FL: CRC Press, 1993 37

"When the bullet emerges from the barrel of the gun, it is accompanied by flame, gas, powder, soot, primer residue, metallic particles stripped from the bullet and vaporized metal from the bullet and cartridge case. The powder results from incomplete combustion of the propellant, as burning of smokeless powder is never really complete. Thus, partially burnt, burning, and unburned grains of powder invariably emerge with the bullet from the barrel. The amount of unburned or partially burned powder exiting depends largely on the burning properties of the powder and the length of the barrel. Contrary to popular misconception, smokeless powder does not explode; rather, it burns. The rate of burning can be controlled by the manufacturer by means of varying the size and shape of the powder grains, as well as by coating them with substances that retard combustion. The size and shape affect the burning rate by controlling the amount of surface area exposed to the flame. The greater the surface area, the faster the combustion."

Nickudu,

That certainly sounds a lot more definitive than what B.S. Barsness has to say on the matter.

What was he thinking?

Dan

If you burned all the powder in the first few inches, velocity would still increase because the hot gases are still expanding.

I tend to enjoy reading Mr. Barsness' work, but he's wrong on this. Which is okay. I mean, he IS human, unlike Jane Fonda.

Muzzle flash is from unburned powder just like the fire that comes out of a nitro-fueled dragster is... unburned nitro. Nitro burns slow, which helps generate power in such applications... but that means that some of it isn't done burning when it comes out the pipes. It's essentially the same thing with most powders.

I'm sure you'd find, if you researched the matter, that the new "low-flash" factory ammo that is sold for defensive purposes contains non-cannister powders with very fast burn rates -- and low charges of same.

Russ

Evening folks,
Looks like Pecos has asked us to attend a gunfight and all I have is a knife!
First off, the disclaimer; Alvin is our ballistics guru and, unfortunately, unavailable for about ten more days. So, I'll try to muddle through as best I can from what I've read and what gems of wisdom Alvin has shared with me.
I believe the data Pecos is referring to in AccuLoad is the pressure curve. When the powder in the cartridge is ignited, the rise in internal pressure is very quick and this peak occurs during the first few inches of bullet movement down the barrel as the pressure of the burning powder/expanding gas overcomes the inertia of the seated bullet (and crimp, if any). As the bullet moves down the barrel, the size of the combustion chamber increases and the pressure curve falls off rapidly. However, the bullet is already moving and gaining velocity. The bullet will continue to gain velocity as long as it remains in the barrel and subject to the expanding gas, thus longer barrels achieve greater velocity than shorter barrels.
Now the question of Barsness' comment. I can't speak for Alvin, but my personal opinion is that MOST of the powder is burned in the first few inches of bullet travel. I think that it is highly unlikely that any powder consistantly achieves a 100% combustion rate in any barrel length. I saw the "sheet test" referred to in one of the comments and I've done that test myself firing through newsprint at various ranges. I've found not only residue but burn spots as well. Anyone who has ever shot Blue Dot can attest to unburned residue that will flare up when exposed to a flame.
There was an excellent series of articles that appeared in Handloader magazine beginning in July 1968 and continuing, intermittently, through March 1971. The articles (12 parts, I think) were entitled "Pressure Factors" and written by Lloyd Brownell at the University of Michigan under a grant from duPont. Wolfe Publishing later combined the articles into a book of the same name. I have all of the Handloaders and the book as well, so it looks like research time.
I know that Alvin corresponds regularly with Geoffry Kolbe at Border Barrels in Scotland. Mr. Kolbe is quite adept at internal ballistics.
I'll see what I can dig up to substantiate the drivel I've posted. All I can contribute is circumstantial evidence and observation. (Sorry, I've been on jury duty for the last two days!)
Regards,
Ed

Shucks, Ed, I wouldn't have invited you into this thing if I'd known you weren't goint to agree with me lock stock and barrel.

No, seriously Ed, I think you pretty much confirmed what most of us were thinking and have observed...and were each trying to say in our own ways.

All of us have seen SOMETHING come blazing out of the barrel at various times and loadings and about the only possible answer is some unburned powder. But it is generally a very miniscule amount.

It occurrs to me what may be happening is the vast majority of the powder is consumed in those first few inches when everthing goes Poof...but invariably there are small abouts that don't get caught up in the initial conflagration and these particles are simply pushed down the barrel ahead of the expanding gas and of course behind the bullet.

So perhaps we may all conclude Barnsness's statement is correct...as far as it goes...but there is a small percentage of powder that doesn't get involved for one reason or another.

Does anyone else see a different conclusion I may be overlooking?

One other thing I should have included in the first post..."Does it really matter?" (excepting extreme situations)

Hell no it doesnt matter! Interesting topic none the less.

Im thinking that if ALL of the powder in a shot was "completley" burned that it would be the exception to the rule.

Isnt it probable that this very subject may explain why a 308 is "more efficent" than a 30-06?

As is illustrated in Nikudu's quote, when a gun discharges what we have done in essence is set off an explosion, a bomb if you will, which will blast everything in its path away.

I think that there could be considered an initial explosion which will closley adhere to the form of the primer fire, and a reactive ignighting of the remaining powder. The more intense the discharge the more rapidly the unburned powder will exit. Not unlike a dog chasing its tail.

Before we get too wrapped around the axle over what we think he wrote, why not read his actual words?

I'm too lazy and too painful of a typist to quote it all here, but you can find the article in the June 2002 issue of Handloader. Page 50.

Just a suggestion to level the field.

Joe.

What we're talking about here is internal ballistics. While Barsness may have knowledge on the subject he is not an expert. I'm not either, but I would have to disagree with him on this one.

What happens when you pull the trigger and fire the primer?

1) The primer actually explodes (powder burns) and totally ignites some of the powder in the case. The pressure from the explosion of the primer and the initial burning of the powder begins the process of moving the bullet out of the case. Some variables to consider are neck tension and crimping plus how much powder gets ignited in this initial step.

2) As the bullet moves the unburned powder is driven along by the initial gas pressure and this powder also begins to burn but only along the edges and mostly the rear edges. Most all of this occurs before the bullet leaves the case but this second slug of powder is mostly consumed very quickly...that is, the part that does actually burn. Forces that act against complete combustion come from sources as quenching of the heat of the powder as it comes in contact with the barrel.

I think you can see that some of the factors that will benefit more complete combustion of the powder are keeping the bullet in the case or nearly so for as long as possible and having as small a powder column as feasible so the primer can ignite more powder in the "initial" step of the process. Tests have also shown that interior case diameters that are about 2x bullet diameter are the most efficient......guess what? We are describing the new "short-fat" cases like the WSM and SAUM....this is why they produce similar velocities using less powders than their longer predecessors.

Now to what many call the tertiary or 3rd zone of powder combustion. Basically this is powder that only partially burns for a variety of reasons and so adds little to the process. This is the powder residue in your barrel...some unburnt and some partially burnt. The more there is of this, the less efficient the process as this powder actually works to cool the other powder that is trying to burn.

Many of these factors can be affected by things like how close you seat bullets to the lands, neck tension, condition of the throat, how easily the bullet obdurates as it enters the rifling and to a lesser extent the rate of twist. Shoulder angle also effects the initial burning as it can affect how the shock of the initial primer explosion affects the base of the bullet.

There is quite a bit of interesting reading on this subject but unfortunately you must be willing to put aside old beliefs and wives-tales and read it with an open mind. Two writers, in my mind, stand out......Dr. Ken Howell and Mic McPherson and one of the better magazines in Varmint Hunter published quarterly.

Remember, it isn't what you don't know that can get you in trouble, it's what you think you know and don't.

No long winded speech here need be written regarding powder burn time in the bore of any cartridge from the 22 hornet to 460 Weatherby magnum. Modern smokeless propelant is completely consumed in the first 16" of your rifles bore. If that were not the case no overcharged cartridge would ever blow up a rifle because it would blow the unburned powder out of the bore but it does not. Why do you think it is possible to blow up a fine rifle if that were not the case. Common sense logic should prevail on this question.

[QUOTE]Originally posted by DB Bill:
[QB]What happens when you pull the trigger and fire the primer?

1) The primer actually explodes (powder burns) and totally ignites some of the powder in the case. The pressure from the explosion of the primer and the initial burning of the powder begins the process of moving the bullet out of the case. Some variables to consider are neck tension and crimping plus how much powder gets ignited in this initial step.

2) As the bullet moves the unburned powder is driven along by the initial gas pressure and this powder also begins to burn but only along the edges and mostly the rear edges. Most all of this occurs before the bullet leaves the case but this second slug of powder is mostly consumed very quickly...that is, the part that does actually burn. Forces that act against complete combustion come from sources as quenching of the heat of the powder as it comes in contact with the barrel.

I think you can see that some of the factors that will benefit more complete combustion of the powder are keeping the bullet in the case or nearly so for as long as possible and having as small a powder column as feasible so the primer can ignite more powder in the "initial" step of the process. Tests have also shown that interior case diameters that are about 2x bullet diameter are the most efficient......guess what? We are describing the new "short-fat" cases like the WSM and SAUM....this is why they produce similar velocities using less powders than their longer predecessors.

Now to what many call the tertiary or 3rd zone of powder combustion. Basically this is powder that only partially burns for a variety of reasons and so adds little to the process. This is the powder residue in your barrel...some unburnt and some partially burnt. The more there is of this, the less efficient the process as this powder actually works to cool the other powder that is trying to burn.

Many of these factors can be affected by things like how close you seat bullets to the lands, neck tension, condition of the throat, how easily the bullet obdurates as it enters the rifling and to a lesser extent the rate of twist. Shoulder angle also effects the initial burning as it can affect how the shock of the initial primer explosion affects the base of the bullet.

There is quite a bit of interesting reading on this subject but unfortunately you must be willing to put aside old beliefs and wives-tales and read it with an open mind. Two writers, in my mind, stand out......Dr. Ken Howell and Mic McPherson and one of the better magazines in Varmint Hunter published quarterly."
__________________________________________________

The above is a good summary of current thinking. A article "A New Look At Cartridge Internal Ballistics" by Robert Smalley in the May "Precision Shooting" discusses shoulder angles and a new concept an outside radius shoulder.

The point of the shoulder angle or radius is that the energy of the primer is deflected to pushing on the bullet with a slight angle which wastes it's energy and those with a very sharp angle deflect it back while those of certain angle deflect the energy towards the unignited slug of powder that the author claims is concentrated at the neck-shoulder area.

I might also add that Mic McPherson and a collaborator have developed and patented (pending) a new cartridge design made to maximize efficiency and performance....just one of the interesting features is a curved shoulder designed to minimize the bad effects of primer shock.

Just remember....to every complex problem there is at least one simple incorrect answer.

My question would be: If John Barsness IS correct that most of the powder is burned in the first few inches of the barrel, why does the formula for free recoil energy include the projectile weight and the total powder charge as the ejecta?
Without info to the contrary, I'm inclined to go with a longer distance-16" sounds about right.
Jury duty for 2 days? Hah! I've been on for 10 already and anticipate 3 more. Murder is so messy.

onefunzr2,
My deepest sympathy. From now on, for jury selection, I going in wearing swim fins, a batman cape and a football helmet. I'm considering singing the Arlo Guthrie song in it's entirity. Maybe that will get me sent back to work where it's safe.
'puck

onefunzr2.....I think what Barness "meant" was that all the powder that is going to burn enough to provide energy actually burns in the first few inches of the barrel.

Unfortunately Barness must have anticapated a higher level of basic knowledge from his readers than he actually got.

A response from Barness....."I simplified all this, perhaps a little over-much in my article in RIFLE, because most readers don't buy it for a chemistry lesson".

In another, previous response he says " Tests done by Homer Powley have shown that all the powder does burn within a few inches of the chamber, and except for a few non-burning solids (such as deterrent coatings) is completely consumed shortly after the pressure curve drops.

Muzzle flash is caused by the hot, still-expanding gases re-igniting when they hit the atmosphere, not by still-burning powder granules. You can blow unburned powder granules out the muzzle, but generally not unless you're shooting a cartridge operationg at much lower temperatures than the powder was designed for. When loading the 45-70, for instance, with IMR4895 to 25,000 psi or so, you'll find unburned powder both in the barrel and on the ground in front of the muzzle.

But the granules of IMR4895 (or H4831) are all burned up within a few inches of the chamber when fired in a 30-06 or any other modern bottleneck cartridge that reaches 50,000 psi or more. Slow powders create more muzzle flash because the gases expand slower, leaving more hot gas to create muzzle flash (and more muzzle pressure). But the gas is NOT created by still-burning powder granules."

Now here's what Dr. Ken Howell says (from Homer Powley's eleventh Technical memo "Muzzle Blast" from December 1964. (I'm not going to do it in quotes but it is what Ken wrote.)

Most practical shooter know about muzzle blast, and a few of them know that unburned powder can be found on the ground a short distance from the muzzle. These few have then jumped to the conclusion that since not all the powder has burned inside the barrel, it is burning outside the muzzle, and this where the balst comes from. Don't believe this.

With normal loads, only about 99 percent of the powder burns inside the barrel. The rest goes out the barrel in the form of splinters - you can tell when you find them. All the powder that is going to burn has done so at the place of peak pressure, which is only a few inches in front of the chamber.

When gunpowder burns under pressure, the solid is converted to a mixture of gases including nitrogen, steam, carbon dioxide, carbon monoxide, hydrogen, methane, and free carbon. All of these-except nitrogen, steam and carbon dioxide - undergo combustion in air. The relative amounts formed depend upon the kind of powder, the temperature and pressure when formed, the presence of catalysts, and the variations during expansion down the bore. They react with each other to change composition.

When these gases come out of the muzzle at high temperature and pressure, they ignite in the air to cause a secondary explosion by combustion and with the formation of a ball of fire. Most powders contain salts of some kind to reduce the blast and flash. Muzzle brakes and flash-hiders tend to spread the gases into cooler air with dilution and so reduce the effect.

FROM ME!

All this from Homer Powley courtesy of Ken Howell and I think this is bascially what Barness meant and amplified on in his latter response. Those who don't know who Powley or Howell are will be excused from further discussions.

When a Diesel turbocharger produces only 30 PSI of pressure, the pressure alone can raise intake temps to as much as 300 degrees. I wonder what temp the inside of a bbl becomes @ 50,000+ psi?