I thought this would be interesting to share. Unfortunately the current edition being sold on Amazon is from a small time bootleg publisher so it's not worth giving a page number but this comes out of the "following the latest bomb crater chapter" in Gallands "the first and the last".
"The me-109 carries only one 20-mm. cannon and two normal machine guns. This could by no means be regarded as sufficient in the fight against multienginrd bombers. This armament, too, constituted an incomprehensible regression in the new me-109F compared with the E series, who's production has stopped the previous year. The latter had two 20-mm. cannons mounted in the wings and two normal machine guns. The one cannon of the new me-109F was of course more modern, had a quicker rate of fire, a better trajectory, and what is more was centrally mounted over the engine and fired through he gun of the propeller. Nevertheless there were conflicting opinions as to whether the new armament should be regarded as a step forward or a step backward. Molders shared Udets opinion that one centrally mounted cannon was better then two in the wings. I regarded one cannon as completely inadequate, particularly as I considered machine guns outdated for aerial combat, merely senseless fireworks. One could hardly impress an enemy fighter with them anymore, to say nothing of multiengined bombers. Naturally I recognized he advantages of centrally mounted weapons. But if the armament consisted of one cannon only, then I preferred two decent rap cannons, especially when I thought of the gradually declining standard in skill and training of the majority of or new pilots, which was unavoidable as the war dragged on. Not every pilot was as good a sharpshooter as Molders or Udet.
This problem of the me-109 armament was also brought to Hitler's notice, how and by whom I do not know. During a conversation he asked me for my opinion. Did I consider the better armament for the me-109 a cannon in the central axis or two in the wings? I did not ponder long: "Better all three." Hitler was pleased. My answer corresponded with his ideas. He used the fact that later development proved him repeatedly correct as an argument in his attempts to put into practice odd ideas of his own in the field of armament and technically, against the advice of experts.
Immediately after this conversation came the order to increase the armament of the me-109F. Two additional 20-mm. cannons were mounted below the wings. These "gondolas" or "bathtubs" as we called them, naturally affected the performance of the plane badly. The aircraft defaced in this was was dad good as useless in fighter combat. But at least with three cannons she had now a firing power with which one could achieve something in the battle with the Flying Fortress.
Later on when the fighter escort of the Americans became more and more effective, the "bathtubs" had to be removed again. The escorting fighters became the primary target. Shooting down bombers took second place. Many favorable chances were missed by neglecting to provide stronger armament for our fighters. Much more suitable was the FW-190 first with two and later with four 20-mm. cannons and two machine guns."
Apologies if there are any mistakes, I am typing this on a cell phone while sitting on the beach.
