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Posted: 1/9/2012 9:48:24 AM EDT
What is the approx. ratio between black and smokeless powder in power by volume ?
The only answer I can find is smokeless is more powerful.
How much more powerful ?    
1.5x- 2x- 3x ?
I realize there is lots of different powder formulas, and lots of variables.
I am just looking for an approximation.
Link Posted: 1/9/2012 9:53:24 AM EDT
[#1]
Quoted:
What is the approx. ratio between black and smokeless powder in power by volume ?
The only answer I can find is smokeless is more powerful.
How much more powerful ?    
1.5x- 2x- 3x ?
I realize there is lots of different powder formulas, and lots of variables.
I am just looking for an approximation.


BP has a maximum velocity of somewhere around ~2400FPS. That means that no matter how many tons of it you cram down a barrel, when it ignites it's only going to produce expanding gas at a certain rate, resulting in a maximum velocity that is slightly lower than that rate.

Same with smokeless powder, but the difference is that the rate of gas expansion is roughly twice as high, so that where BP might get you to 2200-2400 FPS, cartridge guns can get you to 4400-4600FPS. (rough numbers; use google to get more exact).

There is NO direct correlation between 'smokeless powder' and BP. There are certain smokeless powder that can be used in certain amounts to duplicate the velocity of old BP loads (in cartridge guns or in smokeless-safe frontstuffers such as the Savage 10MLII). However, you'll have to have a reloading manual for specifics.
Link Posted: 1/9/2012 9:58:22 AM EDT
[#2]
I'm not sure, but are you trying to use smokeless powder in a black powder gun?
Link Posted: 1/9/2012 10:06:58 AM EDT
[#3]
Quoted:
I'm not sure, but are you trying to use smokeless powder in a black powder gun?


No............Nothing like that
Just me and a friend were discussing different powders,
and he said he had always heard smokeless was more powerful per volume.
I asked how much more and he said he didn't know.
So, off to google and a search agrees that smokeless is more powerful.
I just can't find an answer on how much more.
Link Posted: 1/9/2012 11:06:16 AM EDT
[#4]
Quoted:
Quoted:
I'm not sure, but are you trying to use smokeless powder in a black powder gun?


No............Nothing like that
Just me and a friend were discussing different powders,
and he said he had always heard smokeless was more powerful per volume.
I asked how much more and he said he didn't know.
So, off to google and a search agrees that smokeless is more powerful.
I just can't find an answer on how much more.



I haven't reloaded in many years, so I'm talking in generalities. I also strictly followed reloading books at the time, so I didn't experiment with powders not suitable for a specific application.

You'll need to define what you mean by more powerful. Yes, smokeless is more energetic in general.
For example, a 45/70 round holds roughly 60-65 grains of 2f BP, while about 1/3 of that using IMR 4759 gives equivalent velocity. If you use the same amount of Bullseye as 4759, you'll probably blow up your gun.

In a 45 colt, I used 5.2-5.5gr of 231, I think it holds about 35 gr. 3f BP. Many of the slow smokeless powders are too slow for decent performance in a handgun round.

Black powder has only a handful of granulation/burn rates. Smokeless has many times that and there is the stick vs. ball powder. Then you have the various coatings to control the speed of the burn.Very few of those are suitable for use in a black powder cartridge gun. That's probably why you can only find general statements about smokeless being more powerful, too many variables in that equation.

ETA: Another consideration. BP is classified as an explosive. It doesn't need to be confined to create a pressure wave. Smokeless is a flammable and will not detonate when unconfined, it just burns really fast. So, unconfined, BP is more powerful. Confine the powders in a gun's chamber and you change the results.
Link Posted: 1/9/2012 12:52:16 PM EDT
[#5]
A quick search gives me numbers of:

3 megajoules/kg for black powder

4.6 megajoules/kg for smokeless

I think many of the factors Bob mentioned affect why they are treated so differently when it comes to loading them into a cartridge.
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