well, since the "energy" quotient of this all is derived through the division of V*V*bullet weight in grains by a a known constant, we can simply compare the product of the factors and ignore the constant (which i don't remember).

400gr @ 1800fps= 1800*1800*400=1,296,000,000
250gr @ 2450fps= 2450*2450*250=1,500,625,000

so a HOT 45-70 makes about 15% less horsepower than a 35 Whelen at "standard" velocities.

tell me again why we're having this discussion????

this is before we ever talk about trajectories and ballistic coefficients..