Purpose: target shooting @ KHSC, for fun and as a personal challenge. I am hoping to learn as much as I can, and eventually get involved in the goings-on @ Puuloa.
Not absolutely dead-set on .308, either, as a few other calibers look really intriguing (flatter trajectory, energy retention, less drop, greater velocity, etc.), and as others have pointed out, not sure about bolt vs. semi-auto.
Of course, availability/reloading of ammo is a big consideration, also.
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Sorry, kinda late for advice but I'll throw this out anyway.
If you seriously want to learn target rifle shooting, I would suggest a moderate weight 22 target rifle.
Then learn 4 position rifle shooting with that. It's not as macho as a 308, but neither is the cost of the ammo....
and to become a good rifleman you WILL need a lot of ammo.
Understand that I'm NOT talking about shooting from a bipod or bench now.
Just a mat, jacket, sling, and a scope.
Prone, sit , kneel, stand.
IMHO, This is the best way to learn serious rifle shooting.