ORIGINAL: popeye
drfatguy makes a great point.
I do think that a person needs to be responsible and shoot game with an appropriately designed bullet regardless of caliber. Personally I will not shoot a deer with anything smaller than a 25 caliber, which yes excludes a 243, but thats me. Shoot them with whatever you like as long as it's legal.
Thats crazy popeye, deciding on a gun by the diameter of the bore. A .243 makes a .257 look like a cap gun. It is quite a bit more effective than the .257.