GPR .54 Velocity?

[Moloch]

Hi!

I have just a short question, I have a Lyman great plains rifle in .54 and I am shooting .540 conicals with 300 grains with very good results with 75 grains of 3FG swiss powder.

I am asking for a rough guess of velocity? Any ideas?

I know, I need to get my chronograph!

 

[B.L.E.]

My guess is about 1300 to 1400 fps based on my observation that every grain of black powder is good for about 15 to 17 ft-lb of muzzle energy depending on bore diameter and barrel length and powder brand.

 

[Moloch]

Thank you!