I won't hunt with anyone using a 243 on the prairies anymore. Here shots generally begin at 200 yards distance. I have seen 4 deer lost in the last two years, all to a .243 at distances greater than 150 yards, and all on large deer. I keep telling these 6mm fanatics that it's a freaking varmint cartridge past 150 yards... at least were mule deer are considered... but, No. I spent way too much time tracking wounded deer this fall. The final nail in the coffin was listening to a recounting of an antelope hunt where the shooter (not the fellow on the phone, but his son) shot an antelope at 250 yards and "...saw blood running down it's side but it just stood there." For better than 5 minutes. When they stood up it ran and they chased it for 3 miles before putting it down. I didn't even have to ask: " A 243, Right??" You bet!
Woodland shooting or smaller deer, OK.
Not in my company anymore. No more hunting with anyone who insists on using a varmint cartridge for deer.