With any aircraft, I get 'in plane' with them, pull guestimate amount of lead then relax G slightly and fire even if that means the well under my nose and/or im near totally blacked out. You'll be suprised at how effective it can be, and just how many opponents dont evade by constantly adjusting their plane of manuever.
With the tatergun, you have to lead more and i tend to fire only one or two taters, but occasionally you will hit, and IMO its worth 2-3 taters to end the fight even if its only a 10-20% chance of hit - YMMV. One tater-strike is enough usually.