Is your brass trimmed before reloading? 2.015 is listed as max length but causes pressure problems in three of my blackhole weaponry barrels that have tighter match chambers. I trim everything to 2.005 ...no problems. Brass that is too long will create pressure issues like blown primers and...
Always grease the face of the barrel nut that contacts the barrel. You do not want to torque the steel barrel alignment pin against the aluminum upper. This is especially important for some proprietary nuts for certain free floated tubes.
Decide what you want to do with it? Plink, hunt, etc. Then by the best you can afford.....that way you only cry once. Put the money into your rifle....then scope. You always by a scope. All the common brands will serve you well once you decide on features. I would stick to DPMS based...