If you order at EMF (and Taylors actually), just go ahead and order the out of stock item you want. They will not charge your card, and they will call you to let you know that you ordered something out of stock. Then when it comes in, they will call you again to confirm the order and get your 3 digits.
Sportsman's guide is also taking back orders, with delivery dates in June, but they are not guaranteed. I just had one pushed up a month via email.
Midway has been sporadically getting stock, and will take a backorder on some things. They are pretty good with not taking back orders for things that aren't coming anytime soon.