[lamontcg]

For a UAV hovering over the helicopter pad I would imagine that small arms would suffice.

[stjohnswarts]

Most target shooters couldn't hit a drone that wasn't hovering let alone a sailor who had guns training several years back. A shotgun would be the way to get these guys when they got in close enough.

[quantified]

Shotguns. Automatic shotguns would seem to be right for this.