I would like to buy a varmint barrel for my DPMS AR. I would like to get a 20"-24" barrel. Right now im using a 16" 1-9 twist now and would like to try to keep the same configuration just a longer barrel. Christmas is near so please be gentle im putting this together for my Dad to shoot Prairie Dogs in the spring so if you know of a solid barrel kinda inexpensive, pm me please.