Seriously? The .243 is not suited for deer sized game? Really?
I'll second the comment about being brainwashed into thinking a magnum or a $3 bullet is what's need to kill these super deer that are being found in Canada. Bow hunters watch out !
Its only one of the most popular calibres for a reason in North America when it comes to deer. You find it in every store that sells ammo and the 6mm bullets are plentiful for the reloader. It does the job with little recoil and if you hand load, it can be used for gophers, coyotes and deer.
I have two loads. 65 gr vmax for anything smaller than a deer and then a 95 gr SST for the rest.
I took my buck this year with the 95gr and he took two or three steps before falling like the carpet was pulled out from under him. Shot placement is everything with anything you decide to go with.
It sounds like you are a bit like me. I have a 45/70 GG for elk, moose and bear. The .243 for everything else.
Happy hunting.