EMP rounds - how they work

They split apart, and Jensen drew his CA-4, flicking off the safety catch.
He pulled back the slide to be sure a round was already in the chamber;
there it was, the tip of the bullet glowing with a faint blue halo. The
modified rounds were a gift from Pritchard, and instead of a lead head or a
hollowpoint, they had a tiny pack of conductive gel and a super-dense
capacitor at the tip. On impact, the shots released a small, focused
electromagnetic pulse, supposedly powerful enough to give any electronic
hardware a headache. If they didn’t work as advertised, he wouldn’t be
around to complain about it.

- Deus Ex: Black Light, Chapter 4 pg. 70