RE: 243 or 6mm for deer
Others on the forum have said this but here goes. The 6mm (or 244 rem) is a great heavey varmint cartridge. But it doesn't do so well with heavier bullets. As far as I know, there is no factory 6mm of over 100 grains. My 6mm shoots the 80 gr bullter beautifully but it shoots the 100 grainers very badly.
The .243 has a much better time shooting heavier bullets and there seems to be a better selection of ammo. Although I don't own a .243.
My favourite small caliber for deer is the 6.5x55 or 6.5 sweedish. 140 grainers are available and the round is usually accurate with a good ballistic coeffiecient
for what it's worth
okcmco