Shot placement is always very important no matter what round you are shooting to ensure a clean kill. As for .243 compared to 25.06 the later gives you much increased range & retained energy. As a 25.06 fan & owner maybe I am a little biased. If there is possibility of longer shots then the extra power would definitely useful.

Good Luck with your choice


Ps: My 25.06 is darn fun to shoot.

Canada, I understand your biased towards the 25-06 as I am to the .243.
With a premium bullet compared to an average one in the -06 the differences are minute. Heres a comparo of the two, you will notice the .243 has 200 ft more velocity but has 200 ft-lbs less energy at 300 yds. it has a better coeficciency and is a little flatter shooting, now again this is premium compared to one that is not.
But back to the question I would take the .243 over the .223 for sure it has a lot more power, not to say the .223 wont kill deer its just that the .243 is just a better round all around. But you couldnt go wrong with either the .243 the 6mm or the 25-06, these in my opinion are the best cartridges for whitetail.
243-25-06 comparo

Cool, I'd continue to use the 7mmRemMag on the deer (or elk if you are feeling randy) and pick up a .223 as a you say, as a SECONDARY rifle. Cheap and fun to shoot, easy to "keep your hand in" with. Everyone should own one at least once.

I believe in cartridge spacing. Once you get the .223, then all you need to do is go the other direction and pick up a 375 H&H and your North American battery is complete from rodents to polar bear. Later if you are feeling the need for more rifles, then split the differences between 'em with rifles #4 and #5 by getting a 243 and a 338WinMag.

Ooo Hah!
EKM

Get the 223. Use the 7MM when you feel you need more power than the 223. The 243 is much smaller for deer size game than your 7mm and 223 on average is a better varmit gun than 243. Less cost, less noise. For deer between the 223 and 243, to me its a toss-up. Both will kill deer, niether is real good at it though. IMO.

I would go with the .243 if you are wanting a combo deer and predator gun. I consider the 25-06 before buying a .243 myself, but after years of shooting long action rifles I wanted to to go to a short action for a change. I have never regretted it. Just use the heavier bullets for deer and and the lighter ones for predators. Good luck and happy hunting. CG

If it's a lighter deer caliber that you want, I'd go with the .243. It is a great minimum caliber for deer, and will double as a good varmint gun.
If you want a varmint caliber, the .223 is good and cheap to shoot! It just ain't a good deer caliber!

243 WSSM.............read up on ballistics on Winchester web site....

I have killed deer with both,the .243 would be the better choice...