Have lilke new, fired 10-12 times, Rem. Model 504 rifle and want to trade for AR15 upper. Prefer Rock River 24" SS, flat top receiver, .900+ barrel at muzzle, twist 1/8. Upper needs to be complete w/ bolt and bolt carrier and ready to snap onto lower. You can check out this new Remington high quality rifle on Rem's web site: www.remington.com and get full details. Trades need to be "like new for like new..." Thanks for looking.