Pretty sure Mas Ayoob did a write up too on this.
It goes more into detail about the the gun selection. Started with a .38, then got a couple .357s after shooting those empty decided that auto loaders were better. (9mm and 45, if I remember correctly) If find a link I'll post it.
However, it occurs to the storekeeper that his survival armory might need another firepower upgrade. This time, he decides to try semiautomatic pistols. He buys four, all SIGs, that operate the same way. One is the compact nine-shot P-225 9mm. The other three are assorted versions of the P-220 8-shot .45 auto.
For me this really drives home the importance of mind set. "Refuse to be a victim."