I realy don' t want this to turn into a pissing match but the .223, .222. 221 fireball and .220 swift are not deer calibers. Yes you can kill a deer with one and you can kill a grizzly with a .22 short if you want to bad enough. Most states it is illegal to use under 6MM ie .243 cal. The reasons the larger calibers work better is bullet coefficent, retained energy and cross sectional area. This is an example I use for Hunter Ed. classes;

You have a Corvetee that goes 300mph and run into a building. Now you take the same building run into it with a Peterbuilt traveling a 100mph, which would cause the most damage and achive the most penetration. The Peterbuilt would. Why? Because the corvetee would break down, and lose all it' s energy in a very short distance where as the Truck would plow through and causing massive internal damage and possibly a pass through. Lighter weight balls lose thier energy faster. Pure Physics.

Accuracy is a very important element in any hunting sittuation, But it' s only a portion of the whole picture. You can blow a shot with a .600gr 45/70 just as quick as you can with a 90gr .223 but there is much larger margrine for error with the large caliber. By this I mean if you have a high wind say 20-25mph blowing left to right how much farther to the left do I need to hold the .223 than the larger calibers. Like I said; this is what my opinons are and that' s my nickel' s worth.

Your theory is sound.....sounds like something a politician would say that is!! This coming from the guy who once convinced a group of college faculty that riding a bike is more dangerous than riding a bull. Ain' t statistics wonderful!!!

For one thing, your model, as in all physics, uses an idealized environment and denys things that are vital to inclusion and includes things of slight fallacy.

Firstly, a .223 bullet is lucky to retain 60% of its mass upon exiting a coyote, while a .416 bullet used for CB' s are designed to retain 80% or better (and usually do unless a bone is impacted) of their mass. If both would stop in the body, 100% of the velocity is lost, while if the .223 loses 50% of it' s mass, it loses energy twice as quickly, but, truth be told, it' s much more quickly, since force=mass*velocity, if the velocity decreases by 50% per half-second, and the bullet fragments in half per half second, your energy after the first half-second is 1/4 of what you had upon impact. With a .416, losing 20% of it' s energy per half-second, and the same 50% of it' s velocity per half-second, the resultant energy at the end of the first half-second is 2/5 of the initial value, nearly twice that of the .223' s retention.

If you have a 70gr bullet (.00455Kg) @3000fps (914.4m/s), you yield 4.16Newtons (metric equivalent to ft.lbs.). A 400gr bullet (.026Kg) @2500fps (762m/s) you yield 19.8Newtons, so you have about 4 3/4 times as much energy in the 416rigby, no surprise, my tables have 70gr (.21BC)@3000fps at 1399ft.lbs. and a 400gr (.38BC) @2500fps at 5552ft.lbs., about 4 times the energy in the .416rigby.

What does damage in a high-powered round is the hydrostatic shockwave. If the energy is enough, the CNS will be vibrated to a point of shutting down, commonly known as knocking them in the dirt, the bullet will appear to simply knock them over and nothing moves (other than a small nervous twitch, but the game' s already dead). In both of these rounds used on these game animals, the energy isn' t enough to shut down the CNS, but the shockwave still does the damage. Shooting something with a high powered round is kind of like knocking over the first dominoe in a 1-2-3-4...etc pyramid, one knocks down the next two, and they knock down the next three, and the next four, etc. So, what really gets affected initially is dependant on the face area of the bullet, a .416 spire point bullet can easily have the same face area as a .223 wadcutter even, so the area effected by a round nosed bullet in used in each round would be 3.5times greater in the .416 (.136 vs .0391).

Now, a Cape Buff. might weigh 2000# and a white tailed deer might weigh 150# (both are fairly inaccurate, 2000# is a heck of a bull, and a 150# deer' s a greyhound with a rack or a two year old doe), but as far as it goes, the bullet doesn' t have to affect the entire body to do the deed. The only mass that must be affected is a straight line from the entry point to the vitals, not the tail, nor the nose. A bullet pushes a conical section of semi-viscous liquid (soft tissue). It' s a fair assumption that a cape buffalo is twice as deep to the heart, and I' d imagine that it' s maybe 1.5times as heavy per pound than a deer, even it it were 2 times as heavy per pound, the conical section of soft tissue that would have to be affected would be less than four times as heavy in a CB than in a deer, so with four times the energy and less than four times the mass, the more energy would reach the vitals of a CB than a deer.

So with a .223, you have a shattering bullet inflicting a quarter of the energy upon impact and exponentially decaying in energy every instant after impact, while with the .416, you might be pushing a bit more mass, energy retention is such that the penetration and hydrostatic shock is MUCH more with the big dog than the mouse-fart.

energy is really a poor way to determine if a caliber is suitable for an animal.

I hunt deer most often, and have been fortunate enough to take them with a variety of calibers. Therefore, I' ll write about them because I feel that I know what I' m talking about

You kill a deer with damage, not energy. Therefore, the wider and/or deeper your wound canal is, the better.

A 223 has much more energy than a 357, yet the 357 will kill a deer faster (when fired from a rifle or pistol) at 50 yds. than a 223 b/c it will create a larger wound channel...more of what keeps the critter alive gets destroyed (organs) or lost (blood)

if you are looking for calibers that are very effective on deer, despite low energy, look at the:
(pistol or rifle)- 357mag, 44 spcl, 45 Colt, all with a heavy soft point or hard cast bullet

these calibers do a tremendous amount of damage out to 60 yds when fired from a pistol, and about 100 when fired from a rifle, with reletavely low energy