When you are in the hanger you can see two 50Cals and two 30 Cals. When you are in the pilot seat you can fire the two 50Cals and 720 rounds of ammo displayed on the dash board for these. When you are in the rear gunners position (position 2) you can fire the two 30Cals and 2000 rounds is displayed in the top left corner of your screen.
In a B17 you have umpteen 50 cals, but none are forward fireing so from the pilots position you have no ammo displayed at all.
