The 45-70 cartridge has a muzzle velocity of 1,800 feet per second (549m/s) and a muzzle energy of about 3,000 foot-pounds (4,100J). The 577 Tyrannosaur has a muzzle velocity of about 2,400 feet per second (732m/s) and a muzzle energy of about 4,500 foot-pounds (6,100J). The 577 Tyrannosaur also has more recoil than the 45-70. This is due to the fact that the 577 Tyrannosaur is a more powerful round. If you are concerned about recoil, you may want to choose the 45-70 over the 577 Tyrannosaur.