I wouldn't be so sure. The $200 tax stamp on short barreled rifles, short barreled shotguns, suppressors, and full automatic machine guns has never been successfully overturned in a court.
When the National Firearms Act was passed in 1934, a $200 tax then is about the same as a $1000 tax today.
its amazing how dead our constitutional rights are
I believe in constant dollars it was about the equivalent of $4,000.