Here is a prepper's guide to ammunition calibers and their imperial or metric sizing.
Brewing beer is actually quite easy and, its a free (as in beer) pastime. Yes the supplies might cost money and time, but the methodology is as old as civilization; thusly public domain. The basics are simple and provide a means of making good beer that you can enjoy, share and trade.
The venerable axe is arguably the most useful tool anyone can own. With proper care an axe head can last for multiple generations. You can routinely pick up axes for around $10 at flea markets, estate sales and the occasional yard sale, but we recommend the estate sales. While you are there look for a decent chainsaw if you don't already have one. In one instance we saw a $450 Husquavarna chainsaw go for $30.