CHARLESTON, W.Va. -- THERE'S a comical scene in the 1969 movie, "Butch Cassidy and the Sundance Kid," in which train robber Cassidy wants to make sure the dynamite charge he plants will open the railroad's tough new safe.The scene ends when the boxcar containing the safe explodes in a giant fireball, flattening Cassidy and the Kid, sending splintered boards and timbers flying, and making confetti of the safe's money.The Kid looks up at Cassidy and asks, "Think you used enough dynamite there, Butch?"That scene comes immediately to mind whenever someone tells me he uses a 7mm Magnum to hunt for deer, or when he says he's planning to buy a 10-gauge shotgun so he'll "have enough firepower" to kill a turkey at 30 yards.Make no mistake. A 7mm Magnum will kill a deer deader than four o'clock, and a 10-gauge with 31/2-inch Magnum loads will indeed make short work of a turkey.But are they the right tools for the job?In one sense, yes. They comfortably accomplish the task at hand, which is to turn live critters into meat for the fridge.My personal preference, though, is to more closely match my firepower to the size and toughness of the game I hunt.Just to be clear, I don't do it out of any sense of fairness, or because I have some noble desire to appear more "sporting." To me, it's a matter of efficiency.Not many guys would use a 16-pound sledgehammer to drive a carpet tack. They'd more likely select a smaller, lighter hammer that could be wielded more accurately and with less effort.That's why I sold my old deer rifle, a bolt-action .30-06, and replaced it with a bolt-action 7mm-08.The .30-06 was heavy, kicked like a ticked-off donkey, and wasn't terribly accurate. Factory ammunition wasn't expensive or hard to find, but the rifle's heavy recoil took a good bit of fun out of target practice.The 7mm-08, on the other hand, is lighter, doesn't kick as hard, gives me sub-minute-of-angle accuracy with factory ammo, and kills deer every bit as quickly and cleanly as did its larger-caliber predecessor.To me at least, it's more efficient.So is the bolt-action .22 I now use for squirrels. Like many West Virginians, I grew up hunting squirrels with a shotgun. I started off with a single-shot 20-gauge and later "graduated" to a pump-action 12-gauge.The 12-gauge killed squirrels quite handily. At ranges of up to 30 yards, it was simply a matter of drawing a bead, squeezing the trigger and watching a lifeless bushytail plummet to the forest floor.But like the .30-06, the 12-gauge was a load to carry and kicked pretty hard. Its ammo wasn't cheap, either.The .22, on the other hand, weighs 2 pounds less, has virtually no recoil and uses less expensive ammo. It's dead-on accurate all the way out to 50 yards. To me it feels more efficient.It's possible to downsize too much, of course.Hunting grizzly bear with a .243, for example, would be inhumane and foolhardy. The rifle probably would kill the creature, but probably not quickly. And if the bear decided to charge, the .243 would lack the knockdown power needed to plant a ticked-off griz in its tracks.The key to downsizing is to find just enough firearm to kill critters quickly and cleanly, but at the same time isn't a physical or financial burden to shoot - in other words, enough to open the safe without blowing up the boxcar.Got that, Butch?