Muzzle Velocity Calculator

[jolasa]

Here is a Muzzle Velocity Calculator in Perl programming language: http://dragonflybridge.com/cgi-bin/MuzzleVelocity/Muzzle.pl

Based on the work of Don Miller and published in Black Powder Cartridge News (Winter 2011 # 76)

Comes pretty close when compared to experimental values.

JonS

 

[jolasa]

Tell me how close formula comes to your firing line chronograph results.

JonS

 

[Zonie]

Well, it didn't do so good calculating a .50 caliber roundball @ 177 grains weight loaded in a 32 inch barrel with a 1:60 twist* over 90 grains of GOEX FFFg powder.

Lyman found that combination to give 1844 fps velocity.
The link above said it would be 1349 fps, about 500 fps slower.

Giving it the benefit of the doubt I tried a .50 caliber roundball @ 177 grains weight loaded in a 28 inch barrel with a 1:48 twist* over 80 grains of GOEX FFg powder.

Lyman found that barrel and load would give about 1573 fps muzzle velocity.
The links calculator said it would be 1079 fps, about 500 fps slower.

Now, I'm not saying Lymans data is right but I've fired a lot of shots out of a .50 caliber TC using a 80 grain 2Fg powder load and they always "crack" when their shot.
That indicates to me the ball is exceeding the sound barrier at the muzzle and a velocity of only 1079 isn't going that fast.

It would be interesting to see what our members have been getting with a cronometer with their .50's and an 80 or 90 grain powder load.

* I thought it strange that the rate of twist was not a variable in the calculator. There is no place to insert the value.

 

[Spikebuck]

I think the calculator is giving very slow results compared to actuals. I ran the stats for 90 grs 2f and 230 gr ball and 32" barrel. It was 978 fps. Now I know the calculator uses Goex. I have chronographed my .54 Hawken with that load (only with 777) at 2000fps, give or take a few fps and there is no way Goex is less than 1/2 of 777, in my opinion.

 

[Dalekg6]

Here's what I get. Flintlock, 36" Green Mtn barrel, 1-72 twist, .490 ball, pillow ticking patch, spit lube, Goex 3F. Measured across my Chrony Beta.

70gr 1645fps
80gr 1785fps
90gr 1875fps
100gr 1945fps

 

[juancho]

According to the numbers of Dlalekg6 , He is getting about 15 FPE per grain.
Out of my .45 I get 13.some and from my .54 14.some .I think that that is the only way to gesstimate the speed if you will.
You get out what you put in.But as you can see it is gun/patch/RB/powder specific.No two guns are the same, so once you test your gun you can predict aprox in FPE per grain of powder how much you get out of it.At the end ,at least for me , it goes back to accuracy.No one cares how hot the load was that you miss the target with.I can see it for fun, kind of putting the pedal to the metal.Until something goes wrong.Most powder messures only go to 120 grains, wonder why.

 

[pr.piburn]

In my 32 inch 45 Flintlock 1-60 twist I get 2000
with 90 grs Goex FF. 454 ball, Teflon .020 patch.

 

[CoyoteJoe]

The calculated velocities seem very far off from my expectations based on both actual chronographed loads and on data published by Lyman, Hodgdon, and T/C.

 

[longcruise]

Joe, gotta agree with you on that! :shocked2:

According to the calculator my .54 with 80 grains of 3f in 32" barrel is hitting 994 fps.

I use a chrono frequently and figs run about 400 to 500 fps higher.

 

[Stumpkiller]

Yeah, I think that's a bit under. My 85 gr FFFg load for my 54 it gives 1,089 fps. I'd say it has a flawed powder constant or some such.

 

[Herb]

Here you go, Zonie. In this rifle,two other five shot tests with 80 grains went 1677 and 1626 fps. 120 grains also, two five-shot groups. http://www.muzzleloadingforum.com/fusionbb/showpost.php?post/1087216/

 

[Zonie]

Thanks Herb.

I suspect the person who created the calculator forgot to program in, "add 500 to the answer and then print it out". :grin:

 

[doulos]

That calculator is pretty far off from chrono results. With 110 grains Goex FFG Ive had 1590-1615 out of a .58 cal 34 inch Colerain. Thats about 550 fps faster than the calculator results.

 

[Zoar]

Zonie--Hahahhahaaaa :rotf:

hmmm and .....Seems About True... according to that calculator my standard load for my 58 cal pistol would be about 340 feet per second... um, no way.

 

[Newtire]

Well, it didn't do so good calculating a .50 caliber roundball @ 177 grains weight loaded in a 32 inch barrel with a 1:60 twist* over 90 grains of GOEX FFFg powder.

Lyman found that combination to give 1844 fps velocity.
The link above said it would be 1349 fps, about 500 fps slower.

Giving it the benefit of the doubt I tried a .50 caliber roundball @ 177 grains weight loaded in a 28 inch barrel with a 1:48 twist* over 80 grains of GOEX FFg powder.

Lyman found that barrel and load would give about 1573 fps muzzle velocity.
The links calculator said it would be 1079 fps, about 500 fps slower.

Now, I'm not saying Lymans data is right but I've fired a lot of shots out of a .50 caliber TC using a 80 grain 2Fg powder load and they always "crack" when their shot.
That indicates to me the ball is exceeding the sound barrier at the muzzle and a velocity of only 1079 isn't going that fast.

It would be interesting to see what our members have been getting with a cronometer with their .50's and an 80 or 90 grain powder load.

* I thought it strange that the rate of twist was not a variable in the calculator. There is no place to insert the value.

I got 1785 FPS out of a 32” 1-70 twist using a .495” ball and 80 gr. 2f.