Alastain...

I'm not a guide but I have seen a ton of deer killed in my lifetime...We have 3 family farms so I keep the .243 in the truck...It's used to kill coyotes, foxes, crows, groundhogs, feral dogs, feral pigs, deer, bears and other varmints...

We kill 40-50 deer a year and have done so for 30 years off these farms...In a season we will have somewhere between 12 -18 hunters...As you mentioned, somewhere around 125 yards the boys start missing...I'd say for the average shot as you mentioned that deer is pretty safe out at 300 yards...

That's one reason I stick with the .243, I've used it since 1980 and only lost one deer to it...I've killed plenty between 250-350 yards and simply don't like to take them much past that...Killing a deer at 300 yards is a snap when you can kill crows and groundhogs at that distance...

Doping bullet drop is one thing, doping the wind is another, especially with 100 gr bullets...

If I lived in elk country I'd probably have a 300 Mag, but I don't and a .243 will do for the bears I have to dispatch...