260 rem would be my choice there is a review on the front page of the DPMS. But ammo for the 308 will be much much easyer to come buy. I hand load so my pic is the 260 rem.
That said you can buy a much higher quality weapon for 1500$ if you went with the 6.8 spc. Here is one example from a TOP of the line company. Also if you are MIL/LE they will give you a discount or if you know some one who is have them get it for you. Also this is from the manufacture if you call Grant at G&R tactical he can beat this price. This is more than capable of doing what you want.
Here are your ammo options there are quite a few with good bullets and a bunch for punching paper