define "smallest"What is the smallest cartridge YOU would hunt whitetail deer with?
For me the 223 is a pure varmint round. For hunting deer size game, 243 and up would be a better choice. I don't hunt whitetail, I hunt blacktails on Vancouver Island, and go on a annual BC Interior mule deer hunt. I wouldn't rely on a 223 for a expensive mule deer trip. I would opt for a 270 win and the like. Just my opinion.
Back in the "Day" The 22lr killed just about everything. My Uncle used yo say aim just behind the Ear.
The argument that most people make against the .243 win is interesting. "I've seen more animals injured by a .243 than anything else."
OK. So, who was shooting the .243? What type of hunter is apt to choose (or be given) a .243 to shoot with?
Answer those questions and I think you might be closer to the truth about why the .243 (supposedly) injures so many animals.
How true! The new hunters who are provided with a .243 by their mentors are well-equipped...IF the rest of your formula is followed, i.e. lots of practice combined with careful shot selection.
The hunters who choose the .243 for themselves seem to belong to one of two groups. The first (and smaller) group consists of experienced hunters who know how to shoot because they do a lot of it, and know how to choose their shots on game. The much-larger second group consists of guys who "know" that the .243 is a giant-killer, and use its easy-shooting quality as a substitute for practice and experience. They attempt shots with it that should be either reserved for heavier guns, or passed entirely. Sorry, but it's true: there are many instances in which, due to either range or shot presentation or both, a heavier rifle is called for if the shot is to be taken.
I would use a .243 if circumstances forced me to, but I'm not a fan, and any time I raised the gun to my shoulder I would be thinking "Remember...this is a .243".
What is the retained energy of a 223 out at 300 yds?
As far as a 243's suitability? Sure, why not?
Other than the fact that "It's for women and children"
Of course such a statement sort of shows one as being a tad narrowminded, as women are typically not recoil sensitive. But if it makes you feel manly...fill your boots.
For the record, my discussion of my wife and daughters using a .243 was specific to them, not a generalization. They are all recoil sensitive and I want to give them the best chance at developing good technique/skills. It is so light and fun to shoot, I might even end up using it as my goto deer rifle. Who knows.