I just bought it today, gotta wait ten days here in stupid Ca. tho. The one major difference i see in it compared to the 223 and 7.62x39 is that the barrel is heavier contoured right after the gas block then tapers down to just about the same size as a mini thirty barrel.You can see the difference clearly on the ruger web site. I'm putting a Burris 2-7 x 35mm on it, and need suggestions on a scope base or rings that will allow me to use the iron sights.