newman1,

You can calculate stored energy this way...

STORED ENERGY = VELOCITY times VELOCITY times WEIGHT divided by 450240

where:
STORED ENERGY is in Foot Pounds
VELOCITY is in Feet per second
WEIGHT is arrow weight in grains


so for your example 300 times 300 times 370 divided by 450240 equals 73.960554

of course 74 foot pounds is close enough.