Understanding Calibers: Cartridges, Gauges and Matching the Right Ammunition

Caliber, cartridge and gauge mean different things. Learn how ammunition is named, how to read the markings, and which pairings are unsafe.
Revolver vs. Semi-Automatic Pistol: Which Fits Your Needs?

The advice you were given was probably well meant. It was also probably incomplete, and the part it left out is the part that decides this for a lot of people.