[Zman516]

"...Mustangs were frail-- one bullet in the aluminum cowling and they went down."

That's a little misleading. Only if that "one bullet" happened to hit a coolant line or the radiator, then it was true.

One of the reasons P51 pilots were reluctant to strafe ground targets.

[mikeus_maximus]

You’re absolutely correct! That was the rest of his quote— one bullet through the aluminum cowling that hit a cooling line.