To sum this up.
308 and 1000 yards= very do-able to say the least
168 SMK= Bad choice
SMK for hunting= Bad Choice ( Although you would never hunt with a 308 at 1000 yards any how. so we must assume he meant target shooting
1000 yards and better rifles for this= Yes for sure,BUt if what you have is a 308 go for it ( NOT HUNTING ).
Bart's post is very much in line with reality for sure. His last paragraph is open for discussion though. At 1000 yards from my personnel experience what i have been seeing is the 155 Palma's 155 Hybred's and the 175 SMK's. This is FTR class im refering to.
Most will not go heavier than 175 due to recoil and time back on target. There are a few shooting heavier bullets and doing very well with them.