Black Powder Internal Ballistics Calculator

[Compressorguy]

I find this very interesting and can’t stop playing with different load comparisons. I’ve often wondered how much velocity and energy my muzzleloaders produced and it’s interesting to compare calibers. There’s a lot of additional info as well, like % powder burnt, max pressure, muzzle pressure, muzzle velocity, muzzle energy, etc. I didnt see one like it in the sticky above. Make it stop!


Heres the link below to plug in your own loads.

https://www.p-max.uk/cgi-bin/black_powder.cgi

my .62 smooth rifle vs. .50 caliber rifle

 

[Compressorguy]

My .62 cal Sea Service pistol vs .50 Kentucky pistol

 

[Absoroka]

Is this only available for Swiss powder?

 

[Sparkplug]

Very interesting!

 

[hanshi]

It is indeed very interesting. I have a chronograph I bought over 25 years ago and get average velocity, extreme spread and sd. But the other numbers are not possible with just a chronograph.

 

[Dude]

Seems like it's missing one important bit of data - rifling - length of twist.

 

[borbal]

Seems like it's missing one important bit of data - rifling - length of twist.

Why is that an important piece of data?

 

[Sandro_Ventania]

The most important thing is to find out if it is trustworthy. Has anyone compared the result of this calculator with the speeds you can achieve?

 

[kelvinator]

The most important thing is to find out if it is trustworthy. Has anyone compared the result of this calculator with the speeds you can achieve?

I have, with my Chrony, and others have too, Chorizo I believe.
It is indeed accurate... with powders of comparable oomph to Swiss.

 

[SDSmlf]

The most important thing is to find out if it is trustworthy. Has anyone compared the result of this calculator with the speeds you can achieve?

What has your chronograph told you?

Compared data from a few barrels with different projectiles and the calculator was surprisingly close to what my chronograph saw. Only tried it with Swiss 2F and 3F, but would expect similar data with T7 based on limited previous testing.

I would suggest a confirmation with a chronograph, as every gun is going to give different, at least slightly, results in my experience.

 

[wganz]

Why is that an important piece of data?

Faster twist rates make it harder to push the projectile down the barrel.

 

[SDSmlf]

Faster twist rates make it harder to push the projectile down the barrel.

I seen about the same variation in velocity from gun to gun with the same twist by the same manufacturer as I’ve seen with different twist rates, though I never really study the phenomenon. Powder granulation, powder manufacturer, ball diameter, patch thickness, patch lube, conical, bullet lube, etc, all seem to have an impact on average velocity and shot to shot velocity variation (a real accuracy killer). The program gets you in the ballpark, but without actual range time testing variables the information is useless.

 

[wganz]

@SDSmlf
You are correct. There should be a lot of shooter induced variables with each load manually done. Regardless of how skilled a shooter is, he wouldn’t be as factory load consistent. But, again, that is part of front stuffers that makes them enjoyable.

 

[boberator]

I would also say that the smoothness of the bore makes a difference with more friction in a rougher bore. That also affects gasses blowing past the ball on the way down the barrel.

 

[borbal]

Faster twist rates make it harder to push the projectile down the barrel.

Actually, the energy required to spin the bullet in the barrel is only a fraction of one percent of the translational energy of the bullet, and so not significant, which is why it is not included in the program