wrote:
Didn't the Serbs shoot down a U.S. UAV with a helicopter door gun over
Bosnia a few years back?

Helicopter guns might be a cheap way to deal with low performance
UAV's,
assuming you have a sensor that can detect the UAV and direct the Helo
to the target.
If we are talking about a swarm of UAVs, shooting them down with Helos
is way too slow.
And you better pray the UAVs don't carry Stingers or something similar,
helos are sitting ducks...