Well, according to my SOT, if I sell the MG and it transfers through a dealer, the only person who pays a tax is the buyer, not the seller. I can go FTF inside my state with only one Form 4. I do not have to pay a transfer tax, or acquire a tax stamp if I sell the gun. The tax stamp is bought by the buyer.
Legally speaking, there is no transfer tax. There is a transfer stamp that sells for $200 to the buyer.