Your friend seems misguided. With today's controlled expansion bullets like the Hornady XTP and critical duty loads you literally have bullets that can pass through barriers up to and including car windshields and still have good performance on tissue. The only arena that FMJ loads are better is price. So FMJ is great for training but for defense a good quality JHP is so much better at least in my opinion and if your concerned about penetration a bonded hollow point like Winchester ranger bonded might be a better choice. I know my Glock .40 shots the Winchester ranger stuff reliably and accurately but it's a bit pricey.