Just checking in. I bought my first AR, a DPMS DCM and plan to get involved in the CMP with my oldest son (I have three - 14, 11, and 8). I have two .40 cal Glocks, a 27 (Off Duty) and a 35 (On Duty). I also have an 870. Any advice on the new gun would be appreciated. I am especially interested in good, affordable ammo for the initial range time. I'm sure once we start on competition we will get guidance on the more expensive stuff.