(Taking Zimbabwe as an example, a dangerous game rifle only has to produce 5.3kj of muzzle energy to be legal on dangerous game.) The .577 Tyrannosaur possesses the heaviest free recoil
of all commercially available, shoulder-fired dangerous game rifles - 220lbs into the shoulder.
The load develops a muzzle energy of 4,756 ft-lbs and tooth-rattling free recoil
of 45.6 ft-lbs.
If you calculate the free recoil
of the Ethos 28 firing Federal 3/4-ounce loads at 1,230 feet per second (fps), it's coming back at you with 20.2 foot-pounds of energy.
The Sierra Bullets Infinity ballistics program calculates that a 9-pound .375 H&H rifle, shooting a 300-grain bullet at a muzzle velocity of 2,550 feet per second, generates 42.6 foot-pounds of recoil and 17.5 fps of free recoil
The free recoil
energy calculations exceed many high powered rifles and hover in the same neighborhood as the .458 Winchester Magnum.
The Superformance load generates 26.6 ft-lbs of free recoil
, while the lighter load generates only 15.6 ft-lbs of recoil, a reduction of 41 percent.
That said, most hunters find that a rifle/cartridge combination producing a free recoil
energy of more than 25 to 30 pounds is uncomfortable to shoot.
So while zero doesn't change much, recoil surely does, and as an exercise I calculated the free recoil
energy for the three in my rifle.
The .32 shows a free recoil
energy of 1.5 ft./lbs.; the .380 is nearly double at 2.6 ft./lbs.
I should hasten to point out that the calculation of free recoil
is not what you and I would get (that is felt recoil for which there is no calculation) but rather how much recoil the gun would have if it were fired suspended with no restrictions.
of free recoil
energy from a pistol that only weighs 22 ozs.
Calculated free recoil
energy in foot pounds showed that the Desert Eagle, despite its giving higher velocity with identical loads--due to the integral chamber/barrel configuration--had a significant loss in recoil over a conventional--albeit lighter--revolver.