ok im looking into my first ar and i almost have the money saved. im geting a lwrc a3, and i want a AA 6.5 grendel. at first i was just going to start with the complete A3 lwrc, then i noticed the lowers were bout 550 to 600 bucks. so i thought i could save myself some money and get a cheaper, good quality lower with stag or RRA maybe. the upper is what really counts anyway right? will the lwrc lower be any different than the a stag or RRA lower, the lwrc being made for a piston rifle? i dont want to buy a non-lwrc lower and have problems with the two fiting, or a AA 6.5 upper and it not fit good because i got a different lower.