I order guns from Wal-Mart, two or three a year. All the pistols they have for display are disabled, firing pins removed. Any pistol has to be ordered. As for rifles and shotguns, they carry a good supply on hand, but usually not what I want. I have to order that as well. Ordering is simple, just look through the book and chose what you want. They fill out a form with your name, address, and phone number. They say up to two weeks to get it there, but they usually call within three days. As for what they can get, it depends on what their supplier carries from the factory.
You have to ask to see the order book, and usually you have to see a knowledgable gun counter person. Often the person at the counter is filling in or not a reguler and either does not know anything about the Firearms ordering system, or they are quietly anti-gun and play stupid. When I went to order my Smith And Wesson .360 the young woman behind the counter claimed to not know what to do. I pointed out the book on a shelf under the counter, and she grudgingly brought it out. I opened the book and selected the page. I then pointed out the order form and asked to fill it out. She refused to hand me the order form, making a statement about "No body needs one of those guns anyway". I called the store manager. When the store manager arrived, he helped me fill out the neccessary paperwork for the order. I told him the problem I had with the young woman, and how she refused to help me, and her statement. He said he would talk to her. Saw him a couple of weeks later and asked how gun sales were going. He said, "Good, Good" then he stepped up closer and quitely said, "That woman you had problems with, when I went to discuss it with her she started yelling about how we should not be selling guns anyway. I sent her packing".
I did make a special order for my .35 Whelen through Wal-Mart back in the mid 90s. Eventhou it was not in the book, I talked them into ordering it. NEF barrelled up a standard Handi with a .35 Whelen barrel for me. (I had already talked to Mr. Garrison the CEO at NEF)