I am assuming you are talking about having a gun shipped to you.
Well the short answer is that the gun you want to buy has to go through a local middleman (someone with a FFL license), it cannot be shipped directly to you as a non-licensee.
Basically the way it works is you go to your local gun dealer and tell them you want to order the Saiga. He will tell you a price for transferring the rifle (ususally around $20). Then he will either have you pay him for the rifle plus his transfer fee, and he pays the seller of the rifle, or he will have you pay the seller of the rifle directly.
Either way the rifle is shipped to the FFL holder, not you. Once the rifle gets to your FFL dealers, you then go to his store, fill out the 4473 form, pass a NICS check, and off you go.