Where will you hunt? Are you in an area where deer are large? Do you hunt where average shot distance is under 100 yds, or are long shots the norm? Personally, I'd go with the 308. It won't kill a deer any "deader" on perfect shots, but it will perform better on less than perfect shots. I shoot deer at close range in thick woods. I'd take the 308 for its better selection of heavier bullets that will drive through a deer on angled shots, like the 180 gr round nose soft point. The 750 is not a light weight gun and a 308 won't kick bad at all, especially since it is an automatic.