Velocity Increase/Loss per inch of barrel

[longcruise]

Well, as every professional academic knows, a research report must always end with a call for more research (grant money) :haha: My "research" certainly calls for more.

I did those on a whim when the chronograph was already set up for another project. It would bear repeating with five shots per charge.

As far as practical application of those loads, they are all above my normal charges with that gun. It is pretty much my all around match gun and hunting gun for game up to coyote size. I load it with 45 gr of scheutzen 3f for everything.

What I was curious about was the diminishing returns aspect. Velocity gains were higher than I expected and quite a bit higher than those predicted by local "experts" :stir:

 

[Artificer]

Is it possible that the concept of better velocity and accuracy was hyped by the Hudson's Bay Co. et al since the selling price for a trade gun was a stack of beaver pelts as tall as the gun?

PLEASE understand I am not being critical of you personally, but this is an old myth that just refuses to die. HBC records show they traded guns and other things for a certain number of beaver pelts and not by stacking beaver pelts up to the top of the gun barrel.

Dean2 did an excellent job of explaining this in the following linked post: http://www.muzzleloadingforum.com/fusionbb/showpost.php?post/1484008/

Gus

 

[Artificer]

Well, as every professional academic knows, a research report must always end with a call for more research (grant money) :haha: My "research" certainly calls for more.

:haha: Indeed, good humour mixed with fact there! :haha:

I did those on a whim when the chronograph was already set up for another project. It would bear repeating with five shots per charge.

I understand and agree, though it is a good point to bring up.

Gus

 

[LaBonte]

Is it possible that the concept of better velocity and accuracy was hyped by the Hudson's Bay Co. et al since the selling price for a trade gun was a stack of beaver pelts as tall as the gun?

Gereard - that whole long barrel for a stack of beaver pelts as tall as the gun is one of those myths that has been totally debunked by the historians yet just won't die. Beaver pelts per the primary documentation such as actual period sales records show that plews were bought/sold based on overall weight of your stack of hides (a compressed pack of beaver hides was 90-110 lbs) or by the plew (average weight being 1.5 lbs)

 

[Dphar]

According to what I found, Gearhart-Owens did not take over the Moosic plant from DuPont until 1975. The Lyman Book is copyrighted in 1975. Any Gearhart Powder used in the tests must have been very fresh. I do remember hearing the story about sulfer eating bacteria several times, but never saw anything from an authoritative source.

More importantly, a factor in whether the longer barrels hit harder is the fact that the ratio of the chemical components of black powder have changed many times over the last three centuries. Purity and strength of the chemicals probably also played a part. Testing a modern barrel with modern formulation powder doesn't disprove the possible historical accuracy of the statement, without considering the properties of the chemical mix back then.

Sort of like school kids who lived near schools never packed a lunch because they walked home for lunch. Schools rarely let the kids go home for lunch now. At one time the question "did you walk to school or carry your lunch?" made perfect sense. Today it sounds totally irrational.

If the ratio of chemicals changed from 4-1-1 to a much different formula, perhaps the powder burned with a slower pressure curve in days of yore. For instance, the days before different granualations for different calibers.

The "story" comes from a very good source. But I would not expect to find a letter from Goex detailing it.... Dupont had quit using distilled water well before they sold Moosic. That the powder was hopelessly inconsistent is proved by looking at the data in Lyman. In the 90s it was so bad that new loads had to be developed for every case of powder. Some lots were so bad they were not usable and people sold or gave the stuff away. I used to get letters telling me what lots to buy from the source since when the rainfall was high in the area the bacteria count would go down. So far as "fresh" the bacteria went to work as soon as the water was added to the ingredients. The loose can lids? Had to check the lids in every case... I KNOW the powder was dusty I KNOW the lids were loose. In fact I have some Moosic powder out in the shop I could sift and see how dusty it is....
We also have to consider that the plant never actually made any best grade powder. It was alway military fuze and booster powder. The stuff we were buying back in the 70s was simply repackaged military powder. Where their real bread and butter came from. There is an interesting story related to this but I am not going into that other than to state that I was in the field with the grenades "in stock" so to speak when the "baseball grenade" warning/recall came over the radio..... A friend of mine had thrown two the night before....

Dan

 

[zimmerstutzen]

I did most of my competition shooting in the 1980;s and 1990;s and strictly used Goex for everything. I never had a problem with the powder. In fact I still had some early 1990's powder and used the last of it a few months ago.

 

[azmntman]

ALL mine is from the early 90's and I have had no issues but may just get a order going. Wanna try some swiss.

 

[Artificer]

Thanks to Spence, who steered me to Chapter VII, Range of Barrels, pages 72-94 of W.Cleator's 1791 Essay on shooting, we have one knowledgeable 18th century author's explanation of why they went for longer barrels in the period.

Cleator's explanation is that they felt the longer barrels were needed for the complete "inflammation" (burning) of the powder to get more range and power. The "basic belief" was the powder was gradually burning throughout the barrel length.

However, Cleator noted that there was doubt cast on this "general belief" for some time and as early as 1743 when a committee of the Royal Society conducted tests:

"To determine this, a number of experiments were made by a committee of the Royal Society, so long ago as the year 1743 and by these it was shewn, that, when a barrel was shortened so much that the ball was placed before the powder was upon a level of the muzzle, the unfired powder, was collected from the discharge by means of a cloth spread before the piece, weighed but one twelfth the charge." ”¦”¦”¦And we may therefore safely conclude, that the powder is completely inflamed before the ball or shot arrives at the mouth of the shortest barrel ever employed.”

However, Cleator seems to contradict this when talking about a rifle gun where he suggests that some powder is still burning. He mistakes that the powder is completely burned in shorter barrels. What he misses is the "elastic fluid" he talks about in surprisingly accurate detail and is his term for gas pressure, is still accelerating the PRB down the barrel and not from still burning powder. YET, he also notes there is no significant difference in force applied by longer over shorter barrels. Considering he did not have the scientific equipment we do, he was surprisingly accurate.

Though Cleator gets to his conclusion on useful barrel length through some correct and some incorrect theories, he finalizes that:

"The barrels which we ourselves employ, and which we have found best to answer for every purpose, are from 32 to 38 inches..."

Of course Cleator is talking about sporting guns to fire shot, but the lengths of barrels he proposes and the larger shot carrying to longer distances at the same velocity he mentions, explains why Plains Rifles could be shorter and more accurate at longer ranges than Long Rifle Barrels.

Gus

 

[zimmerstutzen]

There are several leaps of logic in Clears conclusions. Ie powder completely inflamed before the ball reaches the mouth of the shortest barrel. He completely disregards what may have been burned in muzzle flash. Muzzle flash of flame is proof itself that powder is still burning.

 

[gearheart]

Thank you. I will make a note to readjust my perception.

 

[Col. Batguano]

If velocity is that important I would also cup the breech which is good for a consistent velocity gain.
Dan

Could you explain how you cup a breach? I imagine it works under the same principles as a shaped charge.

 

[Artificer]

There are several leaps of logic in Clears conclusions. Ie powder completely inflamed before the ball reaches the mouth of the shortest barrel. He completely disregards what may have been burned in muzzle flash. Muzzle flash of flame is proof itself that powder is still burning.

There is no doubt Cleator got some things wrong, but he came up with the right answer and his writings show an understanding of internal and external ballistics that were way ahead of his time.

There doesn't need to be any unburned powder to have muzzle flash. Muzzle flash/flame is mostly composed of the super heated gas (from the burnt powder) that hits the oxygen rich environment (the air) and ignites violently with the additional oxygen. It is true that any unburned powder expelled into this may or will ignite as well.

However, there is no such thing as perfect combustion of powder in a barrel, no matter how small or large the powder charge. If you have ever seen someone firing a light charge in a rifle, where all the powder SHOULD have completely been burned, and there are sparks that come out of the muzzle - those sparks are unburned grains of powder that are finally ignited by the higher temperature of the gas being ignited in the air. Since black powder leaves something like at least 40 to close to 50 percent of the powder charge as residue, it has been theorized that the unburned grains did not burn because they got coated with enough residue, that they did not burn in the lower temperature inside the barrel OR that there wasn't sufficient sulphur in the grain to burn at the lower temperatures inside the barrel. This last has to do with how well the charcoal, sulphur, and saltpeter were amalgamated into each grain. Oh, some damp grains may also not have ignited inside the barrel and other things.

One myth from the time of black powder rifles all the way through modern rifles is that supposedly the powder is burning throughout the length of the barrel.

People who have read or use the Davenport formula can be and are often confused because of the wording of the explanation of the formula, I.E. “a barrel will burn 11.5 gr. of FFg powder (maximum) for every cubic inch of barrel using a patched round ball.” A common example they use is that the “maximum” powder charge for a .45 cal., 37” barrel is 67.673 or rounded to 68 grains of FFg. However, they knew back then and we know today that if you put 120 grains of 2ffg in that barrel, the velocity will STILL RISE as even the larger quantity of powder was burned in the barrel. That means the larger quantity of powder is burnt in that same barrel length to provide the increased amount of gas pressure that drives the bullet faster.

Back in the 50’s or 60’s, the rather famous ballistician Homer Powley PROVED that the powder in a normal .30-06 load was burned up right at the start of the lands and grooves of the barrel and the Magnum loads took no more than 3 inches for the powder to burn up. Now, I have not been able to find a source that shows what minimum barrel length that black powder burns up in a barrel and that would depend on the quality and grain size of the powder, how large the bore diameter is and other factors. Black powder may take a little more length in a barrel to burn up due to lower gas pressure, but not that much more length.

If there is any doubt that larger powder charges are not being burned in shorter barrels, all one has to do is look a few posts back to Marmotslayer’s Post# 1484633 to see the velocity increases he got when going from 50 grain to 120 grain charges in his 28” long .45 cal., TC barrel.

Even in the shortest 18 inch Jaeger barrels, most charges anyone would have cared to use and withstand the recoil, the powder would have been burnt in that barrel length. The problem was that they needed a little longer barrel than that to get better velocity due to the gas having enough time to accelerate the ball faster. So while they may not or did not really understand WHY the longer barrels shot harder and straighter at longer distances with less powders; they came up with the right technology to do it.

Gus