That is an annoying symptom that came with Cfs-2 , Gun run on , has no bearing on which Fx display you use , It,s a damage result , hardcoded in game , There is also an entrée from mission file , that will show the effect , gun related , Bear Cat posted the only Temp soloution ,, Look in the Dp -- Armour section -- for Machine Gun and Cannon values eg 345 rated armour --and change those to 1200 ,
that delays the hardcoded effect,s, You can imagine 2 or 3 aircraft damaged flying around all shooting at nothing , and wasting fps .