That's not how I'm reading it, this seems to be covering all federal gun control "past, present or future":

All federal acts, laws, orders, rules and regulations passed by the Federal government and specifically any Presidential Administration whether past, present or future, which infringe on the people’s right to keep and bear arms as guaranteed by the Second Amendment to the United States and Article 1, Section 23 of the Missouri Constitution shall be invalid in the county, shall not be recognized by this county, and specifically rejected by this county, and shall be considered null and void and of no effect in this county.

Such acts, laws, orders, rules and regulations include but are not limited to any tax levy, fee, or stamp imposed on firearms, firearm accessories, or ammunition not common to all other goods and services…any registration or tracking of firearms, firearm accessories or ammunition…any act ordering the confiscation of firearms, firearm accessories or ammunition…and finally, any act, whether past, present or future passed by the United States Congress and signed into law by the Federal Government and specifically any Presidential Administration which infringes on the people’s right to keep and bear arms in Newton County, Missouri shall be considered null and void by the county and not recognized by this county.

This seems almost explicitly targeted at the NFA.