And if you do not buy the stamp, it is an open invitation for the BATF to send a SWAT team to you home (compound) and start shooting with those same weapons. Do you remember an incident in Waco Texas that occurred about 10 years ago. The lack of a $200 tax stamp was the prime reason for the search warrant (to look for a gun that might have required that tax stamp).
I beat you to it in post #13. :^])