So talk of Mk19s against zombies lead to the mention that it's not the ones without a top half you need to worry about, but the ones with no bottom half. They're down there crawling around on the ground, under all the regular Roamers, and next thing you know, biting your ankles. (Did I mention my girlfriend's pretty awesome?)
So the light bulb came on, and now these have been added to the anti-zed needs list.