My boy has used the .243 Win exclusively for the past two seasons and taken 8 deer.
I have culled some 50 (+/-) pigs and deer in the past couple years with the cartridge and either 85gr Sierra HPBT-GK bullets or 105gr Hornady A-Max.
It is about as stellar an accurate, low recoil, smooth shooting cartridge for medium game as can be found.
If I had to choose a handful of cartridges to last me the rest of my life...........the .243 Winchester would assuredly be one.