Powder burn rate?

[Bonasa Umbellus]

Newbie here, so bear with me.

Just wondering whether there are faster or slower burning rates for different varieties of BP and its substitutes. I'm well faniliar with this principle as it applies to centerfire rifle and pistol calibers.

For example, I see that 3F is recommended for smaller bores and for pistols: is this because it burns more quickly? I ask because I will be shooting a .50 caliber carbine. Would the shorter barrel of my gun lend itself to a faster-burning powder--assuming such a species exists?

Any and all insight and info appreciated--or feel free to direct me toward a source that describes this.

Thanks in advance.

 

[Larry Pletcher]

In general terms the smaller the grain size, the faster the burn rate. So the huge grain size of cannon grade makes it slowest. The finest of the priming grades are the fastest. There are variations cropping up when you compare different brands. Others may want to add personal experiences with this.

Regards,
Pletch

 

[Zonie]

Your thoughts about the burn rate is correct.

The old rule of thumb was for calibers below .50 use 3Fg powder. For .50 and above, use 2Fg powder.

Many modern shooters have found that their .50 caliber and larger rifles work just as well if not better using the faster burning 3fg powder.
The 3Fg powder also seems to leave less fouling.

Because of the faster burn speed, most folks recommend reducing a rifles 2Fg powder load about 10 percent if they are going to shoot 3Fg powder.

It is impossible to say which powder will work best in your rifle. The only way to find out is to try some of each at a shooting range and find out what your rifle likes.

The modern substitute powders often give the shooter the option of buying powders that are the equivalant of the 2Fg and 3Fg black powder.

For example Pyrodex RS (rifles/shotguns) is pretty close to 2Fg powder in its burn speed and power.
Pyrodex P (Pistol) is pretty close to 3Fg powder.

By the way, I need to mention, if your using real black powder, you can weigh it on a powder scale.

If you are using a substitute black powder, weighing it on a powder scale can get you into trouble.

That's because the substitute powders, along with real black powder are meant to be measured by their volume.
Measuring the substitute black powders by weight causes a problem because they usually weigh less per cubic centimeter or cubic inch than real black powder.

A cc of Pyrodex for instance weighs about 30 percent less than a cc of real black powder but it has the same volume and power as the black powder.