Look over the rules of the class you are shooting in. If ranges are moderate to say 600yds, then the 308 is the ideal choice. If you are going further or can choose any caliber, there is little reason to use the 30cals even out to 1000yds.
My guess is that there is limit to rifle weight like 16lbs or whatever. Unless, you can use muzzle brakes
or build 40lb monsters, the heavy bullet 30cal that do work wonderfully, will beat you to a pulp in one session.
Target shooting is about hitting a target not how much abuse you can tolerate. Recoil will reduce your ability to shoot well, that is why smaller is better.
For moderate ranges, the 6BR or 260 will be ideal. Only shoot a 30cal if the rules mandate it, then the smallest case you can get away with and still launch the highest BC bullets.