Ok, source "Warbird Tech Series Volume 4, Vought F4U Corsair" by "Barrett Tillman".
He mentions that the F4u's outer guns carried 375 rounds a piece, as does the F4U-1 in AH. The 1D and U4 carriers 400rpg on all guns though.
Nothing in the book mentions anything about the 1D or U4 having more ammo loadout, however, the Korean War F4u-4B carried 984 20mm instead of the 924 on the WW2 C modell (as in AH) so the U-4 might have had more ammo aswell.
So to the point, doesn't the 1D have too much ammo? Does any source say that the 1D had increased ammo? If so, what source?