If you pick up an older model 11 or auto 5, be damn sure you have it cleaned out, resprung, and have had parts replaced that need replacing. Every auto 5 and model 11 I have seen looks like they have never been cleaned since they were bought, has a barrel recoil spring is a good 3 inches shorter than it needs, and in some cases has been missing either the bronze brake or the steel ring completely. I have had both my model 11 and auto 5 looked over by a local gunsmith that the majority of his business is fixing and repairing auto 5s. Full cleaning, all new springs, new bronze brakes, new guide rods, and replacing any worn out components were done to get them refurbished and up to spec. Model 11s have a fiber buffer in the rear of the receiver that absolutely needs to be replaced above all else.
You can find them if you look hard enough, and if you are willing to spend the cash to get them fixed up they are worth it. Replacement barrels will cost you more than what you will have in the gun if you aren't going to chop down the originally barrel. Older models with the sliding safety and the one piece carrier can be upgraded to the push button and two piece components, but it will cost a pretty penny. There isn't much in the wya of polymer stocks and fore ends, and some guns will need new stock sets. They are a project gun, but if you get them squared away right they are still amazingly reliable guns.