If your wanting it to be a semi, I'll give you a kind of price point, ballpark figure type of thing. For what your wanting, the starting price in the .308/7.62x51mm game is gonna be right about $900. That will start you off with a G.I. Spec PTR 91 ( which is iron sights only), or a DPMS sportical AR-10 type of rifle without forward assist, no dust cover, or sights what so ever. It only goes up from there. And rember, this is not going to include your optic, which is going to start at, say, $400ish for a decent magnified type. And not every .30 caliber semi auto lends itself well to putting rounds through the same hole at 300, or even 100 yards. I'm a HUGE fan of FAL style rifles, but they aren't going to put a round up a gnats azz at 400 yards either. If your budget were, say, $3000 ( which god knows isn't most people, I'm lucky if my wife lets me spend $700), then you could look into larue, POF, LMT or Amalite type rifles, or even a FN SCAR. But, if you really wanted into this game ( and I am also), I think your best bet would be to buy a DPMS ( preferably the oracle and not sportical). This would give you the platform on which to start, and you can switch the pieces and modify the rifle to your liking over time as the funds become available. Don't worry about " I've never done XYZ before". There are a great many of us here who have and will gladly share our knowledge. To get a good price point look at the DPMS website, fat boy tactical, and sooner stae pawn web site. And before you buy ANYTHING, my advice is to research the hell out of it and the price! And no RIJAS services!!!!!