Recruit, muzzle energy (foot/pounds) is the product of the weight of the projectile times the SQUARE of the velocity. Momentum is the product of the weight of the projectile IN POUNDS times just the plain ol' velocity, and gives you a better idea of recoil in accordance with Newton's Third Law of Motion, but the weight of the powder charge and the velocity of propellant gases must be incliuded in the computation. The constant given to gas velocity is usually 4700 feet per second. So, as you can see, the expression of energy in foot/pounds is prejudiced in favor of high velocities rather than projectile weight, and is thus very misleading. If you are really interested in calculation of recoil, I recommend that you read Chap. XII, The Theory of Recoil, that begins on P 279 of Hatcher's Notebook, by Maj. Gen. Julian Hatcher.

Keep yore powder dry!!