The right tool for the Job: Cartridge Performance on Large game.

One of the most misused statements I often read in hunting magazines is: "Thousands of [Fill in large critter species here] have been killed with [Fill in unreasonably puny caliber here]." This is often the allegation from some of our older gun writers who, from what I can tell, begin extolling the virtues of puny calibers around the age of 50 or so. The claim that a .243 Winchester is somehow appropriate for an animal the size of an elk is preposterous. I do not doubt that many elk have been taken with a .243, I do not doubt either that many elk have been wounded by one either. The problem with making the claim that little guns can kill big beasts belies two falsehoods, 1) that simply because someone has done something in the past makes it feasible for all, and 2) that conditions will always present themselves that make a small caliber on large game option even remotely viable.
The fact that So-and-so has killed a large animal last year with his .257 Roberts doesn't testify to anything. I've seen people do triple back flips on a spring board routine in the Olympics, that doesn't guarantee that trying it myself will pan out very well. I've also seen people use pantyhose as a replacement for an engine belt. Twice in fact have I seen this, and there was a 50% failure rate involved. Simply put, because someone has accomplished something marginal doesn't mean that everyone can. If you challenge this assumption I ask you to call up a guide service and tell them you'd like to plan a hunt for a nice bull and that you plan on bringing your .243 along, and then tell me what they say. I'd bet you'll hear some interesting remarks. These folks have seen people use all sorts of gear and they've seen the best and worst of gear decisions. I will be willing to bet that they gently let you be aware that a .270 doesn't kick all that bad, and after hanging up the phone will shake their head in disbelief and hope that you don't call them back until you get serious.
Most people who will disagree with me will claim that marksmanship, not caliber is the key to bagging big game. Well, hell. If that were true then a peashooter makes the grade then doesn't it? So long as I can put my spit wad behind the shoulder I can take an elk, huh? Wrong. Although marksmanship is the aim for all sportsmen, even a marginal shot into the chest from a .30-06 would be preferred to a good shot from a .243. Let me explain why. First of all the .243 has a 100 grain bullet that could be in anyway construed as being used on an animal over 200 pounds. The weight of the bullet presents the first problem: Momentum. It is easy to slow down a 100 grain bullet at 2700 fps than it is to slow down a 165 grain going 2000 fps. Second let’s say that a shot on an elk from a .243 was able to expand to 50% of its diameter it would be .365" across and would be slowing down incredibly quickly as it sheds mass and as it sheds momentum through the animal. The physics indicate that this combination can lead to disastrous consequences such as an impact that hits a shoulder, and fails to penetrate to the vitals. If the .243 hits a rib at the wrong angle, then your quarry may run a mile before dropping, and if you hunt elk where most people do, he will likely run into the dark timber and become a meal for a hungry bear once the decomposing begins to waft his smell around the hills. Even a perfect marksman cannot predict all the particulars of what the bullet will do even if it hits its mark correctly. The construction of the ribs of animals such as moose, bear, and elk are thick. They are designed to contain and protect these animals that can easily weigh several hundred pounds. Their shoulders are thick, little bullets don't fare well against 1 and 3/8ths inches of solid bone. In the case of bears you have the problem of fat sealing up entrance and exit wounds from a rifle. A little bullet will complicate the matter as the holes from which you want blood to leak from will be less productive.
The likely hood that everything on a hunt will go according to plan is smaller than the likelihood of finding an electron from one of the iron molecules in my rifle somewhere near the moon. It doesn't happen. This carries over to how game presents itself. I have watched enough nonsense television to see that even these actors who hunt 15-20 times per season to film enough for a show often are rarely presented with ideal circumstances. Animals often are bedded down below where you can see their vitals, sometimes they spook up and run, more often than not they're behind a bunch of saplings and are 300 yards away. The confidence level that is instilled by shooting a 30-06 or even a 270 is more comforting than a little cartridge could ever provide. The ranges at which Western game are traditionally pursued tend to be longer. Sometimes you may only see a bull after 5 days of hunting with 1 day left to hunt and you have to decide to take a shoot at 265 yards while he is quartering towards. I'll tell you what; I wouldn't doubt that my .300 Winchester with a factory bullet will drop him with a clean shoulder shot that will anchor him. I have a .243 and I don't have that confidence with deer at that distance even with premium bullets on a windless day.
Ultimately the fact of the matter is that there are certain tools for ANY job. Caliber choice as recommended by the North American Hunting Club is that Elk calibers start at .270 Winchester and the mainstay are the 7mm's and the 30 calibers, a recommendation I agree with. Most guides will approve if you roll into camp with a 7mm Remington or a 30-06. They may however get a little nervous if you show up with a spanking new 338-378 Weatherby, or a 338 ultra mag... but that's a post for a different day.