Selecting the next ammunition order does not instantly change rounds already inside the turret's loading path. Heavy shells placed in a hoist cannot simply be carried back by hand. Removing one would require lifting equipment that the confined handling position may not provide. In practice, the ship would fire the rounds already committed, then receive the newly selected type from the magazine or ready-use supply.
Notable Point · 1:26:29-1:27:16
Why a turret cannot switch shell types instantly
Once rounds enter the hoist, changing ammunition type usually means firing what is already in the loading path first.