To the OP.
If you are looking for a specific machinegun, you need to cast a wide net. That often means looking out of state.
Sturmgewehr.com and GB are good bets.
One dealer who I've worked with is Frank from atfmachinegun.com . He does a TON of volume. He would simply transfer the firearm to the in-state dealer of your choice like jim/boston.
Frank currently has over 50 machineguns listed for sale on GB. If there is something you like and the gun hasn't made reserve yet, he will often talk to you about a direct sale. Frank is well known as a good guy.
He's also one of the few dealers who will guarantee the function of the MGs he sells you.
Don