As a general rule (mine) for handguns:
1) Ten (10) magazines/firearm plus support parts -- springs, followers, bases, if removable -- for heavily used sidearms...
2) At least one (1) spare part for every usable/working/wear part in the firearm; especially the fire-control parts that would be difficult to machine or acquire...
3) Multiple springs -- at least six (6) of each: magazine, internals...
4) 1000+ rounds of ammunition/handgun for training. Self-defense ammunition should/can be less but at least 200 rounds...
5) As much brass, bullets, primers, powder you can afford...
6) Reloading dies and spare parts for progressive reloaders, plus a back-up system (usually a single-stage press)...
A list for your rifles would be different, but their needs should include a good spare bin as well, plus a good supply of ammunition (reloads or military surplus)...
As these parts could be prohibited or restricted if the anti-gunners get in power, they must be stock-piled. Some non-restricted supplies:
1) Batteries (high-grade) for all your gadgets...
2) Extra rifle optics...
3) High quality storage containers (plus safes for all your firearms)...
I'm sure there are many items I missed, but this would make me feel comfortable if the anti-freedom people make life difficult for us. A good and well stocked spare parts and ammo reserve makes me sleep better at night...