BlackPowder Calculator

[Lars-K]

New program I have originally written in Visual Basic. Now I have converted it to html/Javascript as a online tool.

You can test it here: https://weatherby.dk/BP/calc/BlackPowderCalc.htm

All data generated is for Muzzleloaders.

Looks like this:

[megasupermagnum]

I've been playing with it for about 10 minutes, and it's not all that accurate for me. How can you possibly calculate velocity without knowing the bore size? I'm comparing to actual recorded velocities, and it's off by hundreds of FPS. A good example that many people have shot is 70gr Goex FFg, 180 gr ball, 28" barrel, should be ballpark 1600 fps. Your calculator predicts 1341 fps. Another I've tested myself is a 10" 54 caliber handgun, 60gr FFg, 230gr ball, and it tests at 1060 fps. Your calculator predicts 884 fps. My 10 gauge muzzleloader 26" barrels, 100gr Goex Fg, 710gr shot, is around 950 fps. Your calculator predicts 790 fps.

I only found one load that was close. A 45 caliber longrifle with 42" barrel, 90gr FFFg Goex, 130gr ball, should be ballpark 1940 fps according to Goex. Your calculator predicts 1987 fps, which is very close. Drop to 70gr, and it's off by 100 fps again.

[Lars-K]

Hi, the algo for calculating is written by Don Miller. In his formulas there are not taken in consider bore diameter. Also the powder heat value is out of my control.

[indian joe]

I've been playing with it for about 10 minutes, and it's not all that accurate for me. How can you possibly calculate velocity without knowing the bore size? I'm comparing to actual recorded velocities, and it's off by hundreds of FPS. A good example that many people have shot is 70gr Goex FFg, 180 gr ball, 28" barrel, should be ballpark 1600 fps. Your calculator predicts 1341 fps. Another I've tested myself is a 10" 54 caliber handgun, 60gr FFg, 230gr ball, and it tests at 1060 fps. Your calculator predicts 884 fps. My 10 gauge muzzleloader 26" barrels, 100gr Goex Fg, 710gr shot, is around 950 fps. Your calculator predicts 790 fps.

I only found one load that was close. A 45 caliber longrifle with 42" barrel, 90gr FFFg Goex, 130gr ball, should be ballpark 1940 fps according to Goex. Your calculator predicts 1987 fps, which is very close. Drop to 70gr, and it's off by 100 fps again.

I dunno ? dont mean to sound nasty but I am having questions about your numbers? 70 grains of FFg in a 50 ball gun is a mild load - I woulda thought in the 1400ish --
yup have not tested ! I shoot FFFg in my 50 - use 50 grains for a plinker / target load and if I wanna smoke somethin furry would go to about 85 (FFFg) rough guess on that would be about 1700 - maybe 1750.
the law of diminishing returns is very obvious at the upper end of blackpowder loads - its an effective and efficient lower velocity propellant, but chasing the last 100 FPS can get wasteful.

[Lars-K]

Hi. I'm working on a code trying to implement bullet diameter. If somebody could send me some chronograph data it would be nice. Data needs to be using one of the powders used in my calculator.
What I need:

• Muzzle loader data
• Barrel length
• Powder weight
• Bullet weight
• Bullet diameter
• Muzzle velocity in m/sec or fps.

If you prefer, just PM me data to work with.

[Lars-K]

So, code is now up and running, added function for using bullet diameter in the formula. Need some data to verify that my math is correct...

[Lars-K]

Added function: When you put in bullet diameter, the program will automatic calculate the weight of the bullet. If you want to change the bullet value it's still possible.

[longbow]

This would be a good reference to compare with:

https://www.lymanproducts.com/lyman-...ok-2nd-edition

They will all be tested and measured loads done to laboratory standards.

Longbow

[Castaway]

Enlighten me, what exactly is “powder heat value” and what reference did you use to find it?

[longbow]

and this:

https://acrobat.adobe.com/link/revie...5-798766963c42
https://goexpowder.com/resources/load-charts/

[longbow]

Yes! Good question! I was wondering the same thing.

[Lars-K]

Hi, in the case of FFG black powder, a value of K=1544 is commonly used. This means that when the other variables in the formula (barrel length, powder weight, bullet weight, and bullet diameter) are known, the muzzle velocity can be calculated by using K = 1544 into the formula.
This value will change with different powder makers, and a bit from lot to lot. A table of different powders are shown in my program. This data is solely found on the web and collected in my software.

[Lars-K]

@megasupermagnum Bore size is actually not "needed" as long you use round ball bullets. The weight will tell the caliber. But, since wrong values can be used, I will stick to bore diameter.