First before you shoot any rounds through the rifle I would clean it really well.
After you've cleaned your rifle lean it over in the corner of your room, and pull up this web site, and read all the FAQ's at the top of the page before you ever go to the range.
I wouldn't just blast two boxes of ammo into a target randomly, just to break in the barrel, and with the prices of ammo lately, that would almost be a sin!
Some on this board prefer to polish the barrel with bore paste, and cut down on the ammo needed to get the barrel to settle down, and shoot consistently.
I prefer to shoot my guns in and not polish the bore, and the way I would do it is clean it really well first, then go and bore sight it on the 50 yard target, and shoot to get on the paper, then proceed to the 100 yard target.
Once you get it dialed in at 100, clean it really well again, and with the cold barrel, shoot the first shot like you would in a hunting situation like that is the only shot you will get!
Wait a good while to make sure the barrel is cool, and shoot again, following that procedure with the next round.
After about three rounds check your group, and with that you will know if you have a shooter or not, and may have to do some tweeking to get it the way you want.
Do it that way, and you should still have around a box, or box and a half left to work with.
