Looking at the damage on that fuselage, 2 of the exit holes appear to be 12mm (center of cross and bottom right). The elongated hole at the V next to the white section of the cross looks like a tumbled bullet or flak frag damage. The rest is fragmentation damage from an explosive burst that wasn't close enough to blow a large hole in the fuselage. Would be nice if there were other photos showing the rest of the damage.