Just a few notes on ammunition:
I would, with care and consideration of the other party, possibly barter ammo in a WROL situation. I wouldn't worry about one of the rounds you sold or bartered being the one that would kill you. It's a remote possibility, but there is so much ammo in this country that the ne'er do wells almost certainly have their own supply or other sources. It's like selling a car and then worrying that the car you sold would hit you in an accident. After a collapse there will be an infinite number of things you'll have to worry about besides that!
For many years I have implored people to learn reloading and I'm not going to get on the soapbox about it now. You either have the smarts to act on the advice or you don't. I'm beyond caring. Don't bother reading the rest of this post.
I will note a few things about reloaded ammunition that you should be aware of. In a WROL scenario these things probably won't matter, but...
First, it's illegal to sell or barter with ammunition that you reloaded. A lot of folks don't know this, but it's a Federal crime. You're on safe ground if you give ammo away, so I think you're probably safe if you just give away some ammo to a person who bought a gun from you. Make sure you're really giving the ammo away though, and don't adjust the price with or without the ammo. Interestingly, it's legal to sell or barter with ammo that another licensed person or a company reloaded! It's completely legal to sell or barter with new, factory loaded ammunition. Understand that these are the Federal laws and that your state laws may be different. After a societal collapse, I doubt that these will be things will be enforced or even considered. You buys yer ticket and youse takes yer chances.
If you are reloading or even taking steps towards reloading, you should be collecting lead. Currently I get most of my lead from a local, nonferrous metals scrap yard. It's cheap relative to the number of bullets you can cast per pound. Very little lead you find these days will be pure. It's almost always going to be alloyed with other metal. If you can easily press a knife blade into it and make an indentation, it'll be soft enough for most casting. With pure lead, you can make an indentation with your thumbnail. If you find any pure lead (like roof flashings), buy it. Black powder shooters are always looking for pure lead and it's excellent barter material. You can mix pure lead with a little tin or old 50-50 solder to make it hard enough to use in modern handguns.
If you've never cast bullets before, buy a cheap Lee mold on eBay and find a small, cast iron sauce pot at a yard sale or flea market. Then you'll need a small heat source. I use an old propane, Coleman camp stove. A large tablespoon to dip the lead out and pour it into the mold will round out your basic equipment. Oh, get some kitchen matches and use them to "smoke" the interior of the mold. You want the mold's interior to be covered in black carbon. Eventually the mold will become seasoned and you won't need the smoking treatment very often.
If you save your brass (or scrounge it from other sources) and cast your own bullets you can crank out rounds for very, very little. Eventually you'll get to the point where you never buy factory ammo again.
Best
Doc