Not “a” high capacity mag, “several”.
Both my Kahr and my M&P Shield travel with at least one extra [full] mag.
Never leave home without extra mags.
Also, *never* keep your gun or the back up mags loaded with anything but the good self defense ammo (new stuff, not reloaded). FMJ only go in it at the range.
I don’t have a problem with FMJ in my .45 acp due to its lower velicity. In fact, prefer it during the winter in case it’s necessary to penetrate heavy outerwear. In warmer months, I use an alternating mix of Hornaday Critical Defense and Glaser rounds.