1
You Need a License to Buy That
FALSE!
No License is required. What you need to do is pay a tax on the transfer of each item in your possession. The tax is currently $200 for machine guns, suppressors, short-barreled rifles/shotguns, and destructive devices. The transfer tax for Any Other Weapon is $5.
Some states may have permitting or licensing requirements that have to be met prior to the purchase of NFA items, but there is no Federal "Class 3" license. That term is usually used to refer to a Class 1 FFL who has paid the SOT (Special Occupation Tax) fee to allow them to deal in Title II weapons and devices (NFA).