Oh, please. That is the most desperately biased misinterpretation of what I said that I could possibly imagine. I was not and am not advocating taking iffy shots, on either the biggest bruiser or the smallest spiker. I don't take shots unless I know I can make them. But however strongly you may feel about using smaller cartridges to take deer cleanly, you cannot possibly be claiming that a point-of-shoulder shot on a quartering buck...which is absolutely safe and doable with a larger cartridge...can be considered ethical with a .243 or similar out to the same distances. Sorry, it's just not true. It's very trendy to kill critters with the smallest possible cartridge to show how expert a marksman you are. That's fine, if you only take the shots...the admittedly numerous shots...for which those cartridges are suitable.
But, the fact remains that there will be shots, identically well-placed accurate shots, which will result in a quick kill with a sufficiently powerful cartridge but a wound with a smaller one. A broadside double lung shot is wonderful with many cartridges, but a shot on the point of the shoulder or other big bone on a quartering animal is equally effective with far fewer cartridges.
Is it easier to shoot a small cartridge? Of course it is; so what? A large cartridge requires more practice to master....so practice. Of course you shouldn't take shots you are not confident of making...but you should practice enough to be confident in your ability on the shots at which the larger cartridge can excel.
Thanks for the tutorial on low-light target resolution and questionable ethics, but save it for your buddies...because it is not relevant to what I posted.
You sound like one of those light-tackle fishermen, who strive to catch fish on the lightest line possible to achieve some dubious "line class record"...ignoring the increased stress inflicted on the fish throughout the longer battle required to bring it to hand. Yes, very sporting...congrats on your sterling sportsmanship.
So yes, the .243 is enough...just enough...but for animals approaching the 300-pound range, at the ranges at which they may easily be shot, it is emphatically not ideal.
Feel free to insert a sanctimonious last word here; I won't bother coming back.