From Marvel Comics The Punisher Armory No 1
Herstal PN90:
“The U.S. Army thought we needed a more foolproof weapon for the rear-line chair-warmers who might get snuck up on by mechanized infantry.
FN Herstal responded with their PN90, an advanced personnel defense weapon, chambered in a controversial new ammo size: 5.7 mm.
It looks funny, it has no climb, it feels like a BB gun, and it goes right through 48 layers of Kevlar body armor. I like the transparent magazine — you can watch the bullets feed.”
Published by Marvel Comics in The Punisher Armory No. 1, July, 1990