DPMS makes a decent product. The triggers are horrible,and need to be upgraded.
The rifle you're looking at is an entry level rifle,and I wouldn't expect sub-MOA capabilities with it from factory ammo. It could probably do it with hand loaded ammo,but I doubt it with factory.
Save a little more money and get a better equipped rifle with a free floated barrel,and better trigger,and then you will have what you want without needing to change a bunch of stuff on it in order to have a good shooting rifle.
The Panther Bull 20 is a good rifle,but the trigger needs upgrading,the Prairie Panther comes with a decent trigger,and is lighter weight for a little more money.
I shoot a DPMS LR-260H,and the trigger was swapped out before I ever shot it. I put a RRA 2 stage NM trigger in every AR platform I shoot. My 223 and 458 SOCOM are Rock River Arms,and I have always liked their products. The 223 is a 20" Varminter,and it has always performed very well,but I hand load for every rifle I shoot,and don't buy factory ammo.
Texas State Rifle Association
North American Hunting Club