Retriver perk = 6 kills and you have gunship + it last longer. Every game I call 2-3 of them and all together there is almost always gunship in the sky.

I tried to shot it down few times and:

Full clip with X-Pac mortar in single Missle fire mode+ full clip from Reaper Cannon and this shi.t is still in the air. I was shooting point blank into this giant generator.
Does anyone knows how much HP this thing has and are there any better tactics to destroy it???

2 shots from Gauss.