conatct the different companies and have them tell you, if they are allowed to transport ammo. And also transport ammo to private people.
I don`t know how it is in the US but I have been looking into ordering ammo over the internet here in germany and it turned out, it is not worth while.
Taking the price of 150 Euro for 1000 rounds of 9mm Para ammo.
One dealer will take € 10,- for shipment, what is dead cheap, but he is not permitted to ship to a private adress, only to a company adress. Now me working in a bank where security has just been upgraded, havin ammo delivered is not such a good idea.
Another dealer will have the ammo for the same price, but shipment will cost 30 Euros if you live in a town like Frankfurt. If you live in the mountains like I do, another 15 Euro will come to the 30 Euro.
Now having the ammo delivered at a specific time, since I am at work during the day and my wife is not permitted to accept a ammo delivery here, will cost another 15 Euro onto the 30 Euro and the 15 Euro.
So in the end shipment will cost 60 Euro and the ammo 150 euro. That makes 210 Euro and I pay 200 Euro for 100 rounds at my gunsmith.
You will have to read the transportation guidelines very well, because you, as the sender, has the responsibility of the shipment and have to do it exactly as the law wants it.