40 pyrodex ,.310 rb velocity?

[bubba15301]

40 pyrodex p .310rb from T/C Cherokee what velocity am i getting?.? :hmm:

 

[bubba15301]

40 grains pyrodex p

 

[BrownBear]

Yotta pick up the Lyman blackpowder handbook. Lots of good stuff, including ballistics like this in there. They say 40 grains of P gives you 2039 from a 26" barrel, with a max of 70 for 2488. RS gives 1954 at 40 and 2435 at 70.

 

[bubba15301]

i have an old one doesnt have .32 cal listed

 

[BrownBear]

I just checked, and you're right. Good sign I didn't own a 32 back when that was current, isn't it. The latest version has lots more info on rifles and handguns, less on shotguns.

 

[Zonie]

My 2nd Edition says a .32 loaded with Pyrodex P has the following velocities and pressures:

30 = 1837 @ 12,700 psi
40 = 2039 @ 16,100 psi
50 = 2237 @ 19,500 psi
60 = 2363 @ 22,600 psi
70 = 2488 @ 25,600 psi

As you may note, heavy powder charges with Pyrodex P can generate some very serious pressures that get into the smokeless powder range.

If you were shooting GOEX 3Fg powder in the same gun the velocities and pressures are:

30 = 1940 @ 9,400 psi
40 = 2072 @ 9,900 psi
50 = 2203 @ 10,400 psi
60 = 2238 @ 13,000 psi
70 = 2273 @ 15,500 psi

 

[BrownBear]

That's why I never splored the higher end loads with the 32 or 36 with Pyrodex. Those pressures scare me silly.

I had terrific performance with 30 grains of Pyro P in both calibers, and in fact it just gets better as you go down the scale. Current prefered snowshoe hare loads in both calibers is 20 grains, and I really don't care whether it's Pyrodex P or Goex 3f. You (and the hares) just won't notice a difference. If my stocks of Goex are getting low, I switch to Pyro P till the stock is restored.

 

[Jasseji]

any chance to get the formula used for this calculations ?

 

[bubba15301]

my cherokee shoots the40 gr load the best

 

[Zonie]

If your question is about the formula for the various velocities I listed, there isn't one.

These velocities and breech pressures were the results the Lyman Company got while actually testing barrels by shooting multiple shots and publishing the average answers.

The barrels were fitted with strain gauge transducers to determine the internal breech pressures in Pounds per square inch and the velocity was measured using a chronometer.

Their book "BLACK POWDER HANDBOOK & LOADING MANUAL" is a worthwhile book that should be owned by anyone interested in black powder muzzleloading rifles. It also has some interesting data about black powder cartridges that are popular in the U.S.