Could you survive a Zerg invasion?

[Lupino]

In Liberty's Crusade, a Zergling is killed by a shotgun. They aren't bulletproof at all, but that doesn't matters when 10000 of them are running in your direction.

They're also pretty easily killed by the farmers in Shadows of the Xel'Naga.

I think that most Zerg strains are ripped by gauss rifles, but the Ultralisk is another question. Realistically, the Ultralisk should be able to be taken down by anti-tank weapons, however.

I think one survived getting shot by a tank in Shadows as well, that or a bunch of Goliaths I can't remember, but really most modern-day weapons should be enough to kill a Zerg. The problem is that, as you said, there's always one more when your bullets run out.