In the "Gun Digest 2004" the .577 Tyrannosaur with a 750 gr. bullet @ 2400 f/s has 9591 ft/lb.; the .700 Nitro Express with a 1200 gr. bullet @ 1900 f/s has 9618 ft/lb. That is agreat dealof energy fromeither cartridges. [8D][8D][8D]Good luck.