Yup! got a flex site in the Huey, but the Crew Chief still stands 20 or so paces infront of the nose and if he's just short of 6ft, we make a fist to compensate, and the Pilot's both make their respective "Grease Pencil X"......this does work good for Rockets.
As far as the Cobra, the front seater keeps the crosshairs on the target till impact with a TOW missile. (Fly-by-wire, very accurate), the Bird needs to be unmasked and a sitting target itself when doing this. The Hellfire uses the laser to designate and guide the missile. The 20mm, is a matter of understanding lead and lag......and a lot of practise. (A few of us Crew Chiefs with the CO's blessing (off the coast of PI at Tabone Island target range) were allowed to shoot the 20mm, we really wanted to shoot rockets and missile....Fat Chance!)
I was allowed to fire rockets at the Apache Junction Indian Springs Range north of Las Vages, I found that by using the anti-ice element sticking up from the nose compartment and firing as I nosed up, and hitting the trigger (ATTD button) as it passed thru the target worked just fine and hit the truck hulk 4 out of 7 times, the other 3 would impact about 20-30 about the target.