Barrel Volume and Black Powder

[Darkfold]

I'm going to buy a .58 caliber muzzle loader and am wondering if you guys
can give me an idea of how much FFg black powder is enough to efficiently
drive, say, a 525 grain Minié ball without wasting a lot of powder. The
barrel on this carbine-length rifle is 28 inches long. I'll be shooting it
at 25, 50 and 100 yards. Is there a set formula for figuring this out? TIA,

'Frenchie' LaFrance

 

[blafen]

IIRC it is 11.5 grains of blackpowder per cubic inch of bore, although it may be different for conicals.

 

[bingo1952]

That barrel should handle 60 grains of 2F very efficiently with a bullet of that weight. The 11.5 grain per c.i. figure is for round balls. Heavy conicals have more mass and longer barrel times so are more efficient users of powder.

 

[Russ T Frizzen]

Is this a heavy octagon barrel or a light weight barrel? In a strong barrel and using a thick skirted Minie you could go to 90 grains of FFg.

 

[paulvallandigham]

The davenport formula, 11.5 grains per cubic Inch of bore, applies to both Roundballs and conicals. This IS NOT a maximum amount of powder you can put in the barrel, or fire in the barrel. It is the Maximum EFFICIENT amount of powder the barrel can fire using black powder.

There is a law of diminishing returns, and that is what is referred to by Maximum Efficiency. What this means is that when you exceed the amount of powder your barrel can efficiently burn, the amount of increase in velocity for each incremental increase in powder becomes erratic, and over a few increments, demonstrably lower.

A 33" .58 caliber barrel will burn about 106 grains of Black powder efficiently. That is more than enough powder for any purpose using such a caliber rifle, with open iron sights, whether shooting the lighter roundballs, or shooting conicals.

Start with a 60 grain load, and work up from there, first in 10 grain increments, and then with 5 grain increments. Most guns that caliber are shot using 2Fg powder, but some prefer 3Fg. That is part of the " fun " of working up loads for any black powder gun. :thumbsup:

In that 28 inch " carbine " length barrel, the maximum efficient powder charge will be only 85 grains. I don't understand why you would want to shoot a short barreled gun using Black Powder. Its difficult enough to get black powder projectiles up to velocity, considering how slow the powder burns, without shortening the barrel lenths.

 

[mykeal]

In that 28 inch " carbine " length barrel, the maximum efficient powder charge will be only 85 grains. I don't understand why you would want to shoot a short barreled gun using Black Powder. Its difficult enough to get black powder projectiles up to velocity, considering how slow the powder burns, without shortening the barrel lenths.

That's a very surprising comment coming from you, Paul. Are you just being sarcastic?

 

[roundball]

"...give me an idea of how much FFg black powder is enough to efficiently
drive, say, a 525 grain Minié ball without wasting a lot of powder. The
barrel on this carbine-length rifle is 28 inches long..."

T/C makes a 28" x 1:48" x .58cal and lists their conical at 555-560grns...entry level powder charges start at 80grns 2F and step up in 10gr increments to 120grns FFg.
You can download a PDF files of their owner's manual from their website.
You also might want to consider one of the better quality strap on recoil pads for range work.

 

[longcruise]

I'm going to buy a .58 caliber muzzle loader and am wondering if you guys
can give me an idea of how much FFg black powder is enough to efficiently
drive, say, a 525 grain Minié ball without wasting a lot of powder. The
barrel on this carbine-length rifle is 28 inches long. I'll be shooting it
at 25, 50 and 100 yards. Is there a set formula for figuring this out? TIA,

Well, the term "efficiently drive" kinda leaves us hanging. If this is a target gun, 15 or 20 grains would drive the conical through any paper target out there! But, you don't explain your purpose so it's hard to answer your question.

If we assume a few things, then it's possible to come up with some other answers. Realistically, for pure paper work, 40 to 60 grains is going to do the job. If you are shooting a hollow base minie, once you go over 60 grains of powder you will begin to see a gradual loss of accuracy due to the skirt of the bullet overexpanding leaving your conical more and more shaped like a badminton bird.

If this is a hunting rifle, you can do just fine with 60 grains of powder for deer and just a bit more, say 70 or 75 for elk size game. You should be able to obtain adequate accuracy even with a skirted minie bullet at 75 grains.

Maybe this is a carbine length CW style musket that you wish to shoot with minie bullets as done in the old days? If so, the 60 grains or less should be just fine.

OTOH, if you plan to hunt cape buffaloe with a solid base conical or even a hollow base, who cares about efficiency? Load it up heavy and get all the power you can with efficency ignored. :haha: Just because returns on the powder charge begin to diminish, it means nothing in the context of your intended use.

All just the opinion of a shooter who never heard of the Davenport formula. :rotf:

 

[rebelyell]

Sir,

Are you the same Frenchie that is posting on the N-SSA board? If you are looking to shoot N-ssa you don't need full service loads. 50-55 grains should spread the skirts of a minie... You don't need a murderous amount of velocity to bust a tile or flower pot. When I was shooting N-SSA I was firing 45-47 grains FF in my 3-band Enfield. It did fine out to 100 yards (the weak link in the chain was & is the firer-me).
Having said that, each musket is a little different, you will have to experiment to see what the individual weapon likes as far as powder/minie combination...

 

[tg]

"I don't understand why you would want to shoot a short barreled gun using Black Powder. Its difficult enough to get black powder projectiles up to velocity, considering how slow the powder burns, without shortening the barrel lenths."

Another gemstone of wishy washey wisdom, the Germans and others used the short barreled rifle and did rather well according to history, but let us not interject facts that might diminish any value the above pile of bovine excretment might contain..

 

[jdstrang]

The 28-inch barrel is kind of curious: My CSRichmond carbine has a 26-incher, and my two two-band minie rifles, a '55 and a Whitney, both come in at 33. All are N-SSA approved and used in skirmishes.

BTAIM, I would posit that "efficiency" for such a length comes somewhere near 45 gr. of 3f, perhaps 50 of 2f. Any more, and you are wastefully spewing a shower of still-burning powder granules in the wake of your departing minie.

"Efficiency," as well, incorporates accuracy, which is a highly individualistic trait in these sometimes fickle rifles. A grain or so variance in charge can mean a great deal in group size. That's why load development and experimentation is so important in determining an ideal powder charge.

FYI, the aforementioned carbine shoots well with 44.5 grains of 3, the two rifles kind of like 45.5 gr. So, from my experience with these and other rifles like them, I'd say your efficiency peak will come within a grain or two, plus or minus, of 45.

 

[roundball]

"...A grain or so variance in charge can mean a great deal in group size..."

Do I assume correctly that when you say 1 grain difference of powder makes a great difference in group size, you're referring to using real black powder?

 

[CoyoteJoe]

Yes, "efficiency" is a vague term which means different things to different people. I stopped my .58 caliber roundball load development at 100 grains because recoil had become uncomfortable for me and I had passed 1600 fps which gives me a flat enough trajectory for 100 yard shots on game which is about my maximum range for iron sights. So I consider that to be an "efficient" load for myself and my hunting needs.
Another person who is less recoil sensitive and who wants a flatter trajectory could load on up and may consider 150 grains to be more "efficient" for his own needs.

There seems to be a belief on this forum that a barrel can only burn just so much powder and the excess is blown out unburned. That is a very old "old wives tale". It may indeed be true but the maximum amount a barrel can burn is WAY beyond what any rational person would ever shoot and WAY beyond what any manufacturer recommends as a maximum load.
The old Lyman Blackpowder Handbook listed for a .58 caliber, 28" barrel up to 190 grains of 2f.
With 180 grains the muzzle energy was 1585 ft. lb. while with 190 grains it was 1692 ft. lb. That last 10 grains represents an increase in powder of 5.5% while the increase in energy is 6.7%, so one could call that quite "efficient". :grin:

 

[windwalker_au]

Yes, "efficiency" is a vague term which means different things to different people. I stopped my .58 caliber roundball load development at 100 grains because recoil had become uncomfortable for me and I had passed 1600 fps which gives me a flat enough trajectory for 100 yard shots on game which is about my maximum range for iron sights. So I consider that to be an "efficient" load for myself and my hunting needs.
Another person who is less recoil sensitive and who wants a flatter trajectory could load on up and may consider 150 grains to be more "efficient" for his own needs.

There seems to be a belief on this forum that a barrel can only burn just so much powder and the excess is blown out unburned. That is a very old "old wives tale". It may indeed be true but the maximum amount a barrel can burn is WAY beyond what any rational person would ever shoot and WAY beyond what any manufacturer recommends as a maximum load.
The old Lyman Blackpowder Handbook listed for a .58 caliber, 28" barrel up to 190 grains of 2f.
With 180 grains the muzzle energy was 1585 ft. lb. while with 190 grains it was 1692 ft. lb. That last 10 grains represents an increase in powder of 5.5% while the increase in energy is 6.7%, so one could call that quite "efficient". :grin:

well put CoyoteJoe and the gun used for those was a lyman zouave, also in that old lyman handbook the story of val forgett snr in africa in tanzania in 1973 using 26" barreld hawken and buffalo hunter he was shooting 180 grn of fff under a 610grn minie in the hawken
and 125 grn fff in the buffalo hunter with the same minie and took the big five and lots of plains game.
bernie :thumbsup:

 

[longcruise]

, the aforementioned carbine shoots well with 44.5 grains of 3, the two rifles kind of like 45.5 gr. So, from my experience with these and other rifles like them, I'd say your efficiency peak will come within a grain or two, plus or minus, of 45.

Ok, I'll play devils desciple here.

I once did a comparison of the weight of a series of 10 charges thrown carefully from a volumetric measure and here is the result:


Shot 1: 93.5
Shot 2: 94.1
Shot 3: 93.2
Shot 4: 92.5
Shot 5: 92.8
Shot 6: 93.6
Shot 7: 94.0
Shot 8: 92.8
Shot 9: 93.5
Shot 10: 92.2

Average Vel: 93.2
Std Deviation: .63
Extreme Sprd 1.9

The reason for the "shot" number reference is because these were entered in my ballistics spread sheet for auto calc.

As you can see, among ten charges there was an extreme spread of 1.9 grains. that is a percentage of 2% of the average 93.2 grain charge. Unless you are weighing your charges, you are probably getting variations in your thrown charges of around .89 grains extreme spread.

 

[roundball]

"...there seems to be a belief on this forum that a barrel can only burn just so much powder and the excess is blown out unburned. That is a very old "old wives tale"..."

Truer words were never spoken...right up there along side of "shoot it over snow and all the black stuff you see on the snow is unburned powder" :shake:

What's worse is that these arm chair theories continue to be spewed out in spite of everyone else's real actual hands on black powder experience to the contrary...in fact, put aside actual experience and spend just 10 minutes with a chronograph...end of story.

 

[paulvallandigham]

Have YOU ever collected the debris from a load that is over the Maximum charge recommended by the Davenport Formula, that falls to the ground, using a white sheet? Then, pour it all into a small pile someplace safe, like an ashtray, and light it to see what it was, ROUNDBALL? Even you can tell the difference between unburned powder, and burned powder debris.

Or is this your own brand of Armchair theories? :cursing:

 

[jdstrang]

Roundball: Yes, real black powder: Goex 3fg. Dunno why, but in my experience it does make a measurable difference.

Marmotslayer: I referenced weighed charges, not volumetric. I am of the school that holds weighed charges from the same powder lot are more consistent than volume charges. I may be wrong, but the results I have obtained support the argument.

Paul: I agree. I've done enough twilight shooting to see the still-burning powder from others' muskets spraying downrange, and stomped out a few smouldering clumps of dry grass, too. I can't believe that such still-burning residue contributed to propulsion to the degree that did its brethren granules fully consumed within the barrel.

 

[roundball]

Roundball: Yes, real black powder: Goex 3fg. Dunno why, but in my experience it does make a measurable difference.

To be sure I'm understanding what you're verifying with this reply, you're saying for example, 90grns of Goex 3F delivers a nice tight group, but one grain difference like 91grns, opens the group up to a "great difference" ?

 

[longcruise]

Marmotslayer: I referenced weighed charges, not volumetric. I am of the school that holds weighed charges from the same powder lot are more consistent than volume charges. I may be wrong, but the results I have obtained support the argument.

There's no doubt that measured charges are more consistent in weight. One only has to look at my chart to see that!

I'm not sold on the idea that a carefully measured charge would be more accurate than thrown charges. It would take some lengthy experiments to determine it and would probably require several hundred shots of each to see any difference. Just my opinion on that.