Black Powder Pressure

[spotsboss]

Just about every load data chart for smokeless includes the pressure data for each charge, boolit weight and speed.

Why don't we see pressure data for BP?

Any thoughts on this?

[fredj338]

IT's generally not an issue. Fill the case w/ BP, seat the bullet & go. It's been like that for 100s of years.

[Larry Gibson]

IT's generally not an issue. Fill the case w/ BP, seat the bullet & go. It's been like that for 100s of years.

+1

My own pressure tests (Oehler M43) in a 24" test barrel show;

415 gr Desperado 20-1 bullet
70 gr GOEX CTG
Starline cases
Fed 215M primers
19,100 psi
1233 fps

415 gr Desperado 20-1 bullet
Duplex; 7 gr 4759/ 54 gr GOEX CTG
Starline cases
Fed 215M primers
20,300 psi
1263 fps

Larry Gibson

[44man]

Pressure info is out there. But not in smokeless load manuals.

[spotsboss]

+1

My own pressure tests (Oehler M43) in a 24" test barrel show;

415 gr Desperado 20-1 bullet
70 gr GOEX CTG
Starline cases
Fed 215M primers
19,100 psi
1233 fps

415 gr Desperado 20-1 bullet
Duplex; 7 gr 4759/ 54 gr GOEX CTG
Starline cases
Fed 215M primers
20,300 psi
1263 fps

Larry Gibson

Larry,

I would have thought the pressures would be lower than that. If the pressures are not reduced (compared to smokeless), what is the advantage to using BP?

[Wayne Smith]

Larry,

I would have thought the pressures would be lower than that. If the pressures are not reduced (compared to smokeless), what is the advantage to using BP?

"24 barrel". Those are rifle loads, at a guess. They are low.

[Tom Myers]

I would have thought the pressures would be lower than that. If the pressures are not reduced (compared to smokeless), what is the advantage to using BP?[/QUOTE]

Uniform muzzle velocity is just one of the advantages. Check out the Extreme Velocity Spread and Standard Deviation

[Don McDowell]

The Lyman 47 handbook has blackpowder loads with pressures listed under the 45-70 ruger #1 only data . The pressures they got only run about half what the saami specs say it should be.

[Larry Gibson]

SAAMI specs are not what cartridge "should be" loaded to psi wise. It is the psi standards they should not exceed. All commercial cartridges I've tested (23 different cartridges) are not loaded to the SAAMI MAP (Maximum Average Pressure). All are somewhat below the SAAMI MAP. The SAAMI MAP for the 45-70 is 28,000 psi(piezo-transducer) and includes the loads for BP and smokeless powders. TheBP loads are below that as my test report above shows.

Larry Gibson

[Don McDowell]

Lyman's 48 manual they list data for the 40-65 and 40-70, but they did not list any blackpower loads. Altho they did say they determined the pressure to load the smokeless loads to by testing several heavily compressed loads of blackpowder. None of that data exceeds about 18000 cup. For the 45 caliber cases in that 48th edition they held all the cases longer than the 45-70 to the same as their maximum pressures for the "trapdoor" or saami spec levels.
In their 47th edition the 45-70 data tops out around 13000 cup. There's a couple other places that show pressure levels at or about the same.
So that just makes a fella wonder, just how did saami come up with the 28000 psi for the 45-70, which is nearly twice that which the blackpowder lods come up to...

[Larry Gibson]

It was the psi that Frankford arsenal came up with (CUP method) when 45-70 smokeless powder loads were developed for the M1973/79/84 and 88 trapdoor rifles and when they attempted to convert some TDs to 30-40 (didn't work out). 28,000 psi was the MAP forthe TD action.

Larry Gibson

[jdgabbard]

I don't think its about the high pressure number. I think its rather an issue of pressure spikes. While BP is know for giving a solid "push", and smokeless are notice for the pressure curves and spikes.

[Mooseman]

Maximum pressure is also relative to the bore size with BP.
A smaller bore like .32 cal with a 40 gr. charge and a 45gr ball will produce about 8000 PSI where a .50 cal with an 80gr. charge and a 175gr. ball will only run about 6000 psi.
Although it is hard to get much more than about 25,000 PSI maximum from BP I read it has been done in tests years ago where the engineers were able to get 100,000 PSI from a BP load.

[10x]

The Lyman 47 handbook has blackpowder loads with pressures listed under the 45-70 ruger #1 only data . The pressures they got only run about half what the saami specs say it should be.

Those pressures are L.U.P. (Lead units of Pressure) from measuring the deformation of a lead pellet.
Larry has given us pressures in P.S.I. -
There are also C.U.P. (copper units of pressure) to confuse the issue.
L.U.P. , C.U.P, and P.S.I. are not interchangable.

[leftiye]

58 caliber muzzle loader 500 grain bullet 120 grs FFG 12000 psi (IIRC) 1400 fps vel.. 50 caliber 500 bullet 120 grs ffg. approx 21000 psi, 1400 fps. 45/120 500 grain bullet - Accurate data 1400 fps velocity, 32,000 psi. Makes sense, the sectional density goes up as the bore area decreases when bullet weight remains the same, the powder column also gets longer.

[felix]

Actually, we need pressure measurements down the barrel, an inch apart. It seems to me just moving the transducer per shot will work reasonably well because BP produces a very reasonable exactly-the-same pressure curve shot-to-shot. Because BP burns according to granule proximity during burn (as opposed to smokeless), the method of loading MUST be extremely consistent. ... felix

[spotsboss]

Well, you guys have sold me, at least enough for me to give it shot (pun!).

Can of GOEX and all of the other stuff is on the way to me.

When my big Sharps is happy, I'm happy.

[Larry Gibson]

Actually, we need pressure measurements down the barrel, an inch apart. It seems to me just moving the transducer per shot will work reasonably well because BP produces a very reasonable exactly-the-same pressure curve shot-to-shot. Because BP burns according to granule proximity during burn (as opposed to smokeless), the method of loading MUST be extremely consistent. ... felix

Don't need that if the machine give a pressure curve trace with bullet exit from the muzzle as the Oehler M43 does. Knowing the barrel length you can graph out the pressure trace and get that psi data at any point in the barrel easily enough.

Larry Gibson

[mpmarty]

I don't understand the interest in the stinky stuff. I can duplicate any BP load with smokeless and save the mess (speaking of my 45/70 only).

[I'll Make Mine]

I don't understand the interest in the stinky stuff. I can duplicate any BP load with smokeless and save the mess (speaking of my 45/70 only).

Some like "stinky stuff" -- I, for one, find the sulfur smell exciting, as well as the very different sound of the report and the big clouds of white smoke. This is what shooting has been for the bulk of the past six centuries; it's only the last hundred thirty or so years that there's been any alternative to black powder, and for cartridges originally made for black it's still the best way to get in touch with the way they were intended to shoot (not even to mention muzzle loaders and cap-n-ball, where there's really no reliably safe smokeless alternative -- if you don't count "replica black powder" products like Pyrodex and Triple7).

I built a muzzle loading pistol when I was nineteen -- I could have gotten a modern revolver (had a couple friends who would have purchased it for me, and bought my ammunition with my money), but I chose to spend the same money that would have gotten me a bargain basement .38 S&W or .32 ACP on the kit. I spent sixty or seventy hours final shaping and inletting the stockwork, draw filing the flats on the barrel, smoothing and polishing the brass, staining, varnishing and bluing. It was far more exciting to load and fire than a revolver or semi-auto, and even if it had been safe to fire with smokeless (and it surely would be possible to come up with a safe load, probably starting from a very small load of fast powder like Bullseye), it just wouldn't have been the same.