The AC556 is the least-expensive .223 available, yet is of the highest Ruger quality.  It was the gun of choice for police departments in the 1980's and is built like a sporting gun with finer finish and fewer stamped parts than other assault rifles.  3-shot burst can be added to some rifles at extra cost, but is standard on the AC556. Many parts are shared with the Mini 14 rifle and are sold by Brownells at low cost.  Real wood stocks are standard as well as attractive, sturdy folders.  It is the only production machine gun made of stainless steel.  I offer a fine selection of Rugers which have been inspected to ensure good performance.