i was wondering if anyone had any opinions as to what uppers, lowers, barrels, and such. or does anyone know of any good kits to build a SPR, not wanting to spend an arm and a leg, but still wanting it to be a tac driver. Hopefully someone out there will have some good input. Does anyone know of anywhere that sells an 18" barrel and rifle kit? Please help i am having a withdrawal from my SPR from iraq