me an a squad mate were only shooting 37 so i had to hit with the 37 or i wouldnt have seen the hit sprites
I took a P-39Q offline and shot 37mm into a P-38. A tail hit always ripped off half of the elevator and sometimes that side's rudder as well. Outer wing hits would knock off the outer wing. Hits towards the center of the aircraft always exploded it. No more than two hits were required to knock down a P-38, with one usually being enough.
For comparison, I took a Bf 109G-14 with the 30mm cannon. One hit to the elevator resulted in half of the elevator being shot off. One hit to the outer wing resulted in the outer wing coming off. No different than with the 37mm of the P-39Q. One P-38 absorbed three 30mm hits. One knocked out one motor, the other two took off each of the outer wings. A fourth hit was required to explode this P-38.
So, I saw no significant difference between the 37mm M1 and 30mm Mk108 in terms of producing damage. If anything, the 37mm was, perhaps, slightly better. However, shot placement is a major factor.
I have film of the above tests.
My regards,
Widewing