[one good cop]

I recently aquired a rock river upper and am wanting to build a complete gun I've got concerns about a lower should I go with a rock river or a bushy or dpms whats compadable????????? any help is much app...if any one would know you guys would...... probally going with a rock river lower to keep it all together maby

 

[Ridge Runner]

I think they'll all work ok except colt, I have a tromix and an RRA and I've switched uppers back and forth. The RRA NM lower is 350 bucks.
RR

 

[one good cop]

picked up the upper and will be buying the lower soon. i got all the parts for the whole gun left from my bushmasters . 1 stripped reciever and im done.....