In the f86f.lua,you can read this on line 9:
function m3_browing(tbl)
tbl.category = CAT_GUN_MOUNT
tbl.name = "m3_browning"
tbl.supply =
{
shells = {"M2_50_aero_AP","M20_50_aero_APIT"},
mixes = {{1,2,2,1,2,2}}, --
count = 267,
}
In fact,f86f fires both M2_50_aero_AP and "M20_50_aero_APIT". In the game breifing,we can see that f86f fires m3, but in the tacview,it tells us that f86f fires M2.