While its M1911 lineage is clear when disassembled, pistols like this Wilson Combat EDC X9 represent a new generation of compact, M1911-style pistols that carry a double-stack magazine.

The tragedy unfolded in about 30 seconds. The 24-year-old used an assault-style rifle that had a 100-round, double-drum magazine attached, allowing him to fire multiple rounds without reloading.