Problem 1
The ironsights of the .30 cal machine gun on the H-34 door gunner position seem too zoomed out - the camera clips with player character (if he is wearing bulky gear such as grenades) and door frame when angled to the extreme sides - see images.

Problem 2
The ironsights view of the .30 cal machine gun on the H-34 door gunner position allows the gunner to see parts of the helicopter's exterior fuselage when angled to the extreme sides - however the exterior fuselage doesn't render in this view. See images.