the ammo in the Churchill NA 75 is bugged in the damage model in xray mode because if you take 30 rounds of ammo the game shows you having 2 ammo racks filled with 56 rounds of ammo and the ammo rack to the back right of the driver doesnt deplete any of its ammo in the xray model until you have 18 or less rounds in the tank (1 loaded and 17 in the final ammo rack) at which point the 39 round ammo rack vanishes
so in conclusion unless you want to have an ammo explosion on the right side of the tank when penetrated by anything even if you have 19 rounds total in the tank the game still counts the other 38 in the ammo rack as being there even when they are not because the xray modules are bugged and dont count down properly which is the same bug the italian Stug used to have