Historical examples:
* The Firearm Owners Protection Act banned machineguns manufactured before 1986.
* The Federal Assault Weapons Ban banned certain semi-automatic weapons excluding those manufactured before 1994.
Firearm hobbyists need decade-plus forward thinking predictions. What's today legal is a felony tomorrow, unless steps are taken now.
This makes it a volatile guessing game, even more than other hazardous hobbies (cars, aircraft, martial arts, motorcycles, etc.).