Is the upper receiver all I would need to change on this rifle to make it .223 compatiable? Not familiar with the Colt 22lr but if I could buy this and another upper reciever and have two different calibers I would.
http://www.gundealeronline.com/ProductDetails.asp?ProductCode=2245051
The Walther/Colt/Umarex rifle you are referring to is a stand alone unit with absolutely no compatability with true AR-15s other than maybe stocks and handguards.- It’s only made to look like one.
I just looked at one at my gun shop. They had a S&W and a Colt/Walther model. I liked the looks of the Colt better but still at a little over $500…They also had a Colt 6920 for $1100.