As far as I know, this is SOP.
I have done it dozens of times. If I go into my dealer and want him to order something for me, he calls his distributor and if they have it in stock, I get it the next day.
I have done this at several dealers, and as far as I know, it happens every day. This is good for the dealer. He doesn't have to tie a lot of money up in inventory. In fact, he doesn't have to tie up any of his own money at all.
I have also had my dealer get me any number of used guns. I tell him I am looking for a Model 19. He picks up his copy of gunlist and starts making phone calls. Now, I have been in a lot of shops that wouldn't be bothered with actually making an effort to sell something. If that was the only choice I had, I would buy a copy of Gunlist and make the calls myself. Once I decided on something, I would have the dealer order it for me.