As a life long law abiding shooter and collector who lives in California I can say that we have been down this road before. I did a lot of 'panic' buying back in the late 1980s after Bush one (yes....Bush) and Clinton, along with several California State politicians brought us a Statewide AW Ban. This was about 5 years before the 1994 Federal Assault Weapon Ban (that barely expired in 2004).
Nothing expired in California and following the Law, I did Register 11 so named Assault Weapons (ARs AK, HK, Mac, Uzi, etc.etc)
Learning from history I decided to stock up (slowly, over the years) on three specific categories related to future bans and government regulation:
1. America's favorite rifle, the AR 15. I own several and my 4 adult children also own several. If you're not a big fan of the AR platform at least get yourself a couple of stripped Lowers and shove them in the Safe.
2. You can never own too many normal (call high capacity) magazines.
3. The same for ammo. We bought more over the years. Ammo is always a good investment. Here in California we are constantly fighting new proposed laws like a per bullet ammo tax, a ban on mail order Internet sales, ammo ID cards, limits on quantity and reporting to Police if someone buys over a certain amount.
So when this latest gun panic happened, I didn't have to buy anything.
Been there, done that.
Be well, Bob