There are certain things we can no longer have shipped to us in NY because of the "Safe Act" the Knot head in Albany shoved though on us.
The Law is pretty messed up and unclear in its wording, and confuses some out of state dealers.
I myself have not tried powder yet. Best I can offer is.. call a local gun shop and ask them. IF they are a good dealer they will tell you. You could call Midway or Graff & Sons and ask too. I don't see NY restricted on their sites anymore but still not sure.
When the Safe Act was first enacted places like Midway USA sent me emails telling me they would no longer ship ANY ammo or reloading components (Bullets, Primers, Brass, Powder etc) to NY. They have since figured out the law and what they can ship. You cannot have ANY ammo shipped direct to you and it must go though an FFL, i'm not sure on powder and primers though. Some dealers want to charge an FFL Transfer fee same as a firearm to accepts Ammo for you that they don't carry. I have one local dealer that will let you ship to them at no charge, so he is one I do support the most.