Actually, they were spawning in from 29.
They were able to spawn in, perch on top of the giant 13k cliff, and hit us anywhere within the spawn. (including on the base of the hill that they were perched on, they could shoot straight down and not tumble off.) We couldn't hit them because the cliff is too high; and it seemes whenever we put our turrets on them, they'd disappear, no matter how far we were zoomed in or how far graphics were up. I think the spawn should be moved from off the hill (if possible) because the GVs on top of it are nearly untouchable. Only way to get them was to up a plane and climb for over 20 minutes.