ORIGINAL: cayugad
70 grains of Triple Se7en 3f and a 410 gr Hornady Conical with a wad is rated at 1383 fps. So a 460 gr would not be too far behind that. This information is taken out of Hodgdon's Basic Muzzleloading Manual. If that's any help.
Thats 1741 ft-lbs at the muzzle. The same muzzle energy for the 460 would be a little less than 1310 fps. One trick I use for predictingmuzzle energies for two projectiles using the same chargeis to take a ratio of the projectile weights. eg 460/410 = 1.12.
So the 460 weighs about 12% more. Now you can multiply the percentage increase in projectileweightby .45 to get the percentage increase in muzzleenergy, which is .45 x12% = 5.4%.
Then just multiply 1.054 x 1741 ft-lbs = 1835 ft lbs. After one has the muzzle energy, one can use a formula or a ballistics program to calculate the muzzle velocity. Given to the task of predicting velocity for the 460 in the barrel hodgdon tested the 410 with, I would predict a muzzle velocity of 1340 fps with 70 grains 3f 777.