ok so I understand hornady puts out a HIITS rating or something like that, taking velocity, bullet weight, and width into account, so, and I’m sorry this is a dumb question, but how does that compare to muzzle energy?
Muzzle energy is simply a measurement of a projectiles kinetic energy. It’s a widely used baseline measurement to compare cartridge loadings. Muzzle energy measurements only use velocity and weight.
Muzzle energy = ½ x bullet mass x bullet velocity 2
As far as this HITS deal, it’s all been done before. In the late 1940’s, century big game hunter and rifle aficionado John “Pondoro” Taylor developed an equation known as the Taylor Knockout Formula. Taylor, an accomplished big game in Africa, knew that for dangerous game, he needed a round that would put an animal down and keep them there. His formula is just as valid today as it was then, and it shows that muzzle velocity isn’t everything.
It is similar to a scale, the OGW (Optimal Game Weight) formula suggested by E. Matunas quite some years ago, the "results" are presented on what appears to be an arbitrary numerical scale, whereas Matunas' OGW yielded its results (whether you accept them as vaild or not) in pounds of applicable game weight.
The HITS is essentially a formula that is emmulating the OGW scale from Matunas.
For those interested, the formula is;
HITS = (V x W2)/(700,000 x D2)
V = velocity, fps
W = bullet weight, grains
D = bullet diameter, inches
**Note that "W2" means "W squared", likewise for D2
This Hornady HITS is a screwy scale of sorts. It showed a 180gr, .357 Mag loading, when fired from a 4” barrel to be a small game load. Not going to be a lot left of a squirrel when shot by a .357
I feel the HITS scale is simply a reanimation of an earlier model.