I mean actual legislation that was enacted into law on a nationwide basis that restricts my use of a weapon.
If the question is strictly limited to laws that restrict the use of a particular weapon that a person already owns, there have not been many. The 1989 Import Ban placed restrictions on "assembling" an assault rifle, so making changes to covered guns that a person already owned became a real pain. The ammunition capacity restrictions in the 1994 Assault Weapon Ban eliminated the new supply of standard capacity magazines for many guns.
Rather than restricting the use of existing weapons, the laws have generally restricted or prohibited the acquisition of new weapons.
Leedavisone, as a SASS member, how would you like it if all handguns were banned? Assume you could keep the sixguns you already have (we have not gotten to confiscation - yet), but that no new handguns could be produced. How long would SASS last if there was a fixed and dwindling number of sixguns? I don't think that SASS would be an attractive activity if it became limited to leverguns and scatterguns.
At any rate, the government doesn't have to stop people from shooting in SASS matches if laws are passed that will eventually result in a lack of guns or ammo to use in SASS matches.