Southeast Missouri I'd take deer out to 125 yds at the most, but as a rule under 75 yds mostly. Now up here in northern Missouri we see and can shoot deer up to 50- 500 yds. Shooting at deer at over 300 yds (for me) has to be taken from a solid rest with no wind nor distractions, It would definetly have to be a broadside heart lung area type shot. My rifles are super capable of these distances but I'm not, as I only practice from 100 yds.. My scopes are zeroed 3 inches high at 100 yds so they should be money at 300 yds, but I'm the weak link in the chain, I have to use a solid rest,, so last year I bought one of those Primos "trigger sticks" tripod, and it's super solid man, Last year I was carrying the damn thing, but dropped it when my buck jumped up and I shot him off-hand at about 75 yds or so.
I wished I had a 300-500 yd range here to use, but I don't so I practice every weekend at the local MDC range.