Velocity Increase/Loss per inch of barrel

[George]

Higher Velocity gives a flatter trajectory and thus more practical accuracy, both for shooting at variable ranges without having guess as much on how much to hold off, plus the wind and other environmental factors don't have as much time to act negatively on the bullet.

That's very true, and I use the "point blank range" method in a lot of my shooting, so I'm familiar with the concept.

For the old claim that longer barrels "hit harder" than shorter barrels, there has to be a significant difference in velocity between barrel lengths and the only way to test that is by using the exact same load, in the same barrel, at different barrel lengths.

Also true. In both instances, though, it's true only if you are not allowed to add more powder as needed in the shorter barrel to compensate for the change in length. Both ideas tell us interesting things about how our guns work, but we aren't locked into using the same charge in the real world. I can make the short barrel shoot flatter and harder than the long one if I choose.

Spence

 

[Artificer]

For the old claim that longer barrels "hit harder" than shorter barrels, there has to be a significant difference in velocity between barrel lengths and the only way to test that is by using the exact same load, in the same barrel, at different barrel lengths.

Also true. In both instances, though, it's true only if you are not allowed to add more powder as needed in the shorter barrel to compensate for the change in length. Both ideas tell us interesting things about how our guns work, but we aren't locked into using the same charge in the real world. I can make the short barrel shoot flatter and harder than the long one if I choose.

Spence

Spence,

Thank you for this added information and I very much agree with you.

The reason I started this thread was to test the 18th century general belief that "longer barrels shot harder and were more accurate than shorter barrels" - would stand up to real world testing. I am trying to figure out why this old belief got started and whether it was actually true. It is something like what you mentioned in your thread on "Why we believe..." (at least I think so, though I could be wrong about that).

18th century gunsmiths and customers did not have the test equipment we have today. That does not mean they were stupid, it just means they did not have the capability to test things like we do today. So their conclusions from empirical evidence may not or do not stand up to real world testing.

Since modern testing does not show enough differences in velocity or drop or energy when using the same powder and PRB between 30" to 44" lengths of a barrel, then it seems likely or probable that this was not the reason for their belief that longer barrels were more accurate or the other benefits mentioned.

Shorter and slightly larger diameter/thickness barrels shoot every bit as well as Long Rifle Barrels, again, if not more so. We know this from Plains Rifles. We also know it from comparing Rifles to Rifle Muskets during the WBTS where period testing actually showed the shorter "Rifle" with a slightly thicker barrel was more accurate than the longer barreled Rifled Musket by British Tests and at long ranges. We also know that thicker modern barrels shoot more accurately than lighter weight barrels. In each case, the slightly heavier barrel weight gives the accuracy advantage from more uniform barrel vibrations. Jaeger rifle barrels often were heavier or larger in thickness/diameter than Long Rifles for the length of the Jaeger barrel and that would have given them an advantage of better barrel vibrations, unless the barrel was on the REALLY short end of Jaeger barrel length.

Longer sight radius does aid in getting the best accuracy out of a rifled bore/gun, but that also has limitations on how much is gained at what barrel lengths. I admit I am skeptical this was the reason they thought longer barrels were more accurate, both from the fact that 33"-36" barrels in plains rifles proved as accurate, if not more so than Long Rifles with PRB's and from a lot of modern experience in Long Range Iron Sight gun building and watching the best shooters shoot those guns.

So far, I believe there is one thing that definitely would or at least could have shown 18th century gunsmiths and customers that longer barrels were more accurate and that would have been had the shorter barrels had twists too fast for medium to heavy powder charges. Since many Jaegers seem to have been rifled "one turn in the barrel," that would often give them too fast of a twist for medium to heavy powder charges that would at least equal the accuracy of the Long Rifle Barrels IF the Long Rifle Barrels were also rifled "one turn in the [longer] barrel" or at least a slower twist.

Now, I do not pretend this is the main reason or only reason that longer barrels were believed to have been more accurate in the period. Nor do I pretend I have "all the answers." I am open to other reasons why 18th century folks may have thought that Long Rifle Barrels were more accurate, etc., etc. than short or mid length barrels. I would like to see other theories tested, though, so it can be proven.

Finally, I am open to the possibility that 18th century gunsmiths and customers just believed longer barrels were more accurate, etc., etc. and did not really have good evidence or proof to back it up.

Gus

 

[George]

Finally, I am open to the possibility that 18th century gunsmiths and customers just believed longer barrels were more accurate, etc., etc. and did not really have good evidence or proof to back it up.

You might enjoy reading An Essay on Shooting, by W. Cleator, 1791. He has a nice discussion on why shooters of his time came to believe fowling pieces with long barrels were better, and did a lot of work testing the validity of that belief. Pretty sophisticated stuff, and surprisingly modern in many aspects. It is this book which frequently reminds me that many of the arguments of his time are still being discussed today. We are doing it, right now. :grin:
http://books.google.com/books/about/An_essay_on_shooting.html?id=Q3ECAAAAYAAJ

Spence

 

[Artificer]

Finally, I am open to the possibility that 18th century gunsmiths and customers just believed longer barrels were more accurate, etc., etc. and did not really have good evidence or proof to back it up.

You might enjoy reading An Essay on Shooting, by W. Cleator, 1791. He has a nice discussion on why shooters of his time came to believe fowling pieces with long barrels were better, and did a lot of work testing the validity of that belief. Pretty sophisticated stuff, and surprisingly modern in many aspects. It is this book which frequently reminds me that many of the arguments of his time are still being discussed today. We are doing it, right now. :grin:
http://books.google.com/books/about/An_essay_on_shooting.html?id=Q3ECAAAAYAAJ

Spence

Thank you for that link. I have read it through a few times before, but I lost the link when my old computer crashed. I will be sure to add it to my saved files now that you supplied the link. :thumbsup: :hatsoff:

Gus

 

[Dphar]

Has anyone done a definitive test of how much velocity is lost from a muzzle loading barrel firing a .45 or .50 cal. PRB with black powder (not a BP substitute) as the barrel is shortened one inch at a time from say a 42 inch length down to 20 inch length?

I am referring to using the SAME barrel, with the SAME powder charge, with the SAME size ball and patch and lube. IOW, the only thing that would change is the length of the barrel?

If someone has, please let me know the results per inch of velocity loss.

Gus

Unless using Swiss powder the testing has to all be done with the same lot of powder. Current GOEX, for example,is better than their Moosic powder, but the then variations resulted in the contradictory data in Lyman's original BP book. Variations were present within the same can of powder due to deterioration in the can.
If I were after best velocity with a I would not use a barrel shorter than 38" at least in the larger calibers like 50-54. If velocity is that important I would also cup the breech which is good for a consistent velocity gain.
Dan

 

[Artificer]

Dan,

That is a good point about the powder being the same kind, date of manufacture, lot, and even down to can or cans to get the most reliable results. Also, the better powder it is, the more uniform and reliable the results. I meant these things, but probably should have been more specific. Thanks for pointing this out.

Thanks for your input.

Gus

 

[zimmerstutzen]

1. Lyman did cut some of the barrels tested from longer lengths to shorter lengths. They also tested those same barrels at their different lengths with different charges. The 58 cal Zouave barrel was chopped from 32, to 28, to 26, to 24 and 22 inches. But a 58 caliber presents a shorter larger diameter powder columne in the bore and more complete burning over a much shorter barrel length.

2. An 80 grain charge for a 50 caliber barrel is the load at the point of diminishing returns for a 26 inch barrel, Testing that charge in longer barrels would be expected to show only moderate velocity increases, until the barrel is so long that the ball actually starts to slow down from friction.

3. When Lyman tested a 50 cal barrel, they cut it from 43 in to 32, to 28 and 26. the results of 80 grains of FFG were 1854fps, 1777, 1692 and 1690. However those lengths with 110 grains of FFFG were 2190, 2065, 1954, 1957. In both cases, the difference between a 26 inch barrel and a 28, were negligible. Is that because there is no difference, or because some of the powder burns up in muzzle flash, or some other factor.

4. If you compare the figures Lyman got from a 43, 40, 36, 32 and 28 inch 45 cal barrel (same barrel) the results are even stranger. using 70 gr of GO FFG the velocities were 1969, 1924, 1975, 1972 1994. Higher velocities at shorter lengths.

 

[longcruise]

4. If you compare the figures Lyman got from a 43, 40, 36, 32 and 28 inch 45 cal barrel (same barrel) the results are even stranger. using 70 gr of GO FFG the velocities were 1969, 1924, 1975, 1972 1994. Higher velocities at shorter lengths.

These kinds of variation can be explained by sample size. If they shot two or three shots per length, they could easily get those differences. For velocity averages I consider five shots to be absolute minimum and prefer ten.

SD and extreme spreads can be kept to a minimum if the bore is carefully wiped between shots, but a combination of poor barrel prep and not enough shots in the sample can get to those kinds of differences.

 

[longcruise]

1969, 1924, 1975, 1972 1994. Higher velocities at shorter lengths.

The decline from 1969 to 1924 and then back up to 1975 point to small sample or poor bore prep. Most likely both. If you throw out the 1924 then the remaining four are not that far off.

Other things that I have observed that lead to velocity variations is consistency of the patch lube application and changes in patch material.

Also, addressing the diminishing returns scenario, I did a test a few years back with a .45 caliber TC with 28" barrel. The powder was Scheutzen 3f. If you look at the velocities below you will see that the velocity increases were not falling off all that much.

Disclainer: I have stated above that five shot averages are a minimum and ten shots prefered, however, this test involved only one shot at each charge due to time constraints and a diminishing powder supply. On this particular day I had no intention of doing any testing but it came to mind while at the range. It is also the reason that I skipeed the 110 grain load. Thee was not enough powder left in the can to do it.

50 grains
1517

70 grains
1680 +163

90 grains
1865 +185

120 grains
2031 +166

 

[Billnpatti]

"The "Auld Dictum" is that the longer 42-44" barrels in Long Rifles were supposedly more accurate and harder hitting than shorter barrels."

This may be true due to the longer barrel being capable of effeciently burning more powder than a shorter barrel. If it can efficiently burn more powder, it would "hit harder" than a shorter barrel. That's my best guess anyway.

When one looks at the data from both Rice and Dixie's tests, the results are puzzling at best. If you plot the data, it makes no sense at all. :idunno:

 

[zimmerstutzen]

It occurred to me that perhaps the conventional wisdom arose back during the days of corned powder.

 

[Artificer]

Thanks for adding this information.

I agree with Marmotslayer on the reasons for some of the results seem "a little strange." I also theorize that just like some lengths of a modern rifle barrel , when it got cut down and tested for velocity loss and when a surprising result popped up at some lengths, Mechanical Engineers have explained that happened to be a length of the barrel where the vibrational wave was more uniform at that particular length.

Though of course I can not be absolutely sure because I was not there when Rice did their testing, I think they got more uniform results because being a well respected maker of ML barrels; they were more knowledgeable of ML barrels and very careful in the preparation, testing, cleaning, etc. like Marmotslayer mentioned. It was in their interest to be as accurate as possible in the testing, so they would know their product better and possibly/probably help determine how well different lengths of their barrels would shoot. It does not make sense to offer barrel lengths or twists that won't shoot well and of course that makes and keeps their customers happy.

Gus

 

[Dphar]

1. Lyman did cut some of the barrels tested from longer lengths to shorter lengths. They also tested those same barrels at their different lengths with different charges. The 58 cal Zouave barrel was chopped from 32, to 28, to 26, to 24 and 22 inches. But a 58 caliber presents a shorter larger diameter powder columne in the bore and more complete burning over a much shorter barrel length.

2. An 80 grain charge for a 50 caliber barrel is the load at the point of diminishing returns for a 26 inch barrel, Testing that charge in longer barrels would be expected to show only moderate velocity increases, until the barrel is so long that the ball actually starts to slow down from friction.

3. When Lyman tested a 50 cal barrel, they cut it from 43 in to 32, to 28 and 26. the results of 80 grains of FFG were 1854fps, 1777, 1692 and 1690. However those lengths with 110 grains of FFFG were 2190, 2065, 1954, 1957. In both cases, the difference between a 26 inch barrel and a 28, were negligible. Is that because there is no difference, or because some of the powder burns up in muzzle flash, or some other factor.

4. If you compare the figures Lyman got from a 43, 40, 36, 32 and 28 inch 45 cal barrel (same barrel) the results are even stranger. using 70 gr of GO FFG the velocities were 1969, 1924, 1975, 1972 1994. Higher velocities at shorter lengths.

The power they were using was manure. There were very significant changes in the powder in the same can. They were using untreated ground water to make the powder at Moosic even with the late Dupont production. They used to have steam heated drying rooms and used used sterile or distilled water from the boilers. No bugs. Untreated water has sulfur eating bacteria in it. They would actually eat the sulfur in the powder while it sat in storage and would only stop if the 02 level in the can dropped. If the can was not sealed they never stopped. It was not unusual in the 1990s to have 1/4 of the powder unusable due to "fines" and other dust. Many cans came out of the case with loose lids. So Lyman would use the top 1/2 of the can for some of the testing, use the bottom 1/2, then open a new can and get some decent powder for awhile they they would get toward the bottom of the can again..... It was not noticable in MLs but in loading BPCR ammo the dust was very apparent when the powder was drop tubed and the threw away a lot of powder when dust started to show in the cartridge case.... Lots of it in some cases.
So basically their data is "garbage in-garbage out". Short barrels making higher velocity is the tip off. Since they were loading MLs they likely did not notice the dust or did not realize what its meant.
Dan

 

[Artificer]

I appreciate the info on test problems and results you have provided.

I was particularly interested in your results on diminishing returns. I’ve shot a .45 cal., hand built, Post AWI rifle with a 39” straight side Douglas barrel with Siler lock since the mid 70’s, but never used a powder charge as high as your results.

I was fascinated that when going from 50 grains 3FG to more than doubling the charge to 120 grains, the velocity only went up 1/3 of the original 50 grain charge.

Do you happen to know if a 120 grain charge of 3Fg was used in .45 cal rifles Pre or Post AWI?

Thank you,
Gus

 

[Artificer]

Dan,

Very interesting info on the "powder problems" Lyman had with their testing. Thank you.

Gus

 

[zimmerstutzen]

So how did Lyman get similar numbers using Curtis and Harvey powder made in scotland.

What evidence is there that the gearhart owens powder used by Lyman had the sulfur eating bacteria?

 

[zimmerstutzen]

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.

 

[Artificer]

It occurred to me that perhaps the conventional wisdom arose back during the days of corned powder.

Did you perhaps mean the days of Serpentine Powder as in through the 17th century? Corning became the common way to make powder in the 18th century as an improvement over Serpentine. In the 19th century, Corning was improved again by forming "press cakes" of powder under mechanical pressure while the powder was wet/damp?

Gus

 

[gearheart]

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?

 

[Artificer]

We know the quality of powder varied, even rather late in the 18th century and here is a period example:

Christiansbrunn, the 9th September, 1773

Most valued Friend Martin Baer,

At your request I have prepared [completed/finished] a good rifle and sent it over to Mr. John Hopson together with 4 pounds of Powder. The rifle is decorated [inlaid] with silver wire and well made, as well as tested and she shoots right well. It has a double trigger, so that you can fire with the triggers either unset or set. Between the triggers there is a screw with which you can make it lighter or harder to fire. There is also a ball puller with which you can pull the ball out no matter how rusty she gets. She costs 8 pounds all together and with the powder @ 3 shillings per pound makes twelve shillings, for a total of L8.12.-. Because it is very good powder I have added two pounds more than you requested. I hope it will suit you well. You can write me a couple lines to let me know how you like it. Together with friendliest greetings I am your faithful

friend and servant,

Christian Oerter

Gunmaker


This is impressive to me because Christian felt the powder was so good that he assumed the rifle owner would not object to doubling the amount of powder that was ordered. I also think Christian MAY have been hedging his bets as by providing good quality powder, the customer probably would not use poorer quality powder and blame the loss of accuracy on Christian's rifle rather than the poorer quality powder that was commonly available in that area and in that time?

In some of his recent works, Dr. De Witt Bailey has a number of period quotes from British Officers complaining about how bad their powder was in the AWI. Now this is also interesting as such complaints did not seem to be leveled just a few years earlier in the FIW, by the British Officers serving here then.

During the period, powder makers knew that the wood the charcoal was made from had a lot to do with the quality of the powder. By at least the early 19th century, they also realized that powder quality was affected by the humidity on the day the powder was broken up into grains from the press cake. Just as today, the way the powder was stored also had to do with the quality of the powder when it was actually used.

What I DON'T know is if they fully realized that the amount of compression/resistance of the ball or shot had a notable difference in the way the powder performed? A bare ball that would roll or slide down the barrel shows a marked decrease in velocity over a patched ball.

It is very interesting to me that "Screw Barrel" pistols were made in the late 17th and early 18th century, but then were dying out or died out by the mid to late 18th century. I think the oversize ball would have supplied more compression and thus higher velocity than a patched ball. That would have aided poor quality powder in developing higher pressure and thus more velocity and "a harder hitting ball." Did the quality of powder get enough better towards the middle to end of the 18th century that the extra cost of making the screw off barrel was no longer necessary?

Gus