Here is the big deterent. In 1934 the Thompson SMG sold for $195.00 and the NFA stamp was $200.00. A steep price to pay for a Honest person wanting a machine gun.
As a side note:
Frequently, people refer to NFA weapons as “Class 3” guns. This is actually a misnomer. The National Firearms Act breaks firearms down into two basic categories: Title I and Title II. Title I guns are the guns with which most people are familiar, rifles, shotguns, and handguns. Title II guns are the aforementioned machineguns, silencers, short-barrel rifles, short-barrel shotguns, destructive devices, and “Any Other Weapons.” The confusion comes from years of misinformation, or lack of information regarding the definitions within NFA 34.
Commonly, dealers who buy, sell, and trade NFA Title II weapons are known as “Class 3 Dealers.” “Class 3” actually refers to a tax-payer status of federally licensed firearms dealers, or FFL’s. In order to deal in NFA Title II weapons, an FFL must pay an annual Special Occupancy Tax, or SOT. A Class 1 SOT is for a licensed firearms importer. A licensed manufacturer pays a Class 2 SOT, while a dealer pays a Class 3 SOT. The amount of the tax is mostly based on the class, with an additional factor being the gross annual sales of certain SOT’s. Since people wishing to buy an NFA Title II weapon most often buy them from dealers who are Class 3 SOT’s, they came to be simply known as “Class 3 dealers.”