Remember when author Chip Kidd published a picture of this cover in his book and said that Superman "would NEVER so much as consider using a gun against his enemy"?
Well, in the story this cover is supposed to represent, Captain Marvel didn't use one either. Read it and see.
Captain Marvel makes use of the plane to save lives, not take them.
Not only did Captain Marvel not use any machine guns in this story, nobody even got killed when he sunk the submarine. This story makes it clear that everyone on board was saved. I don't think Captain Marvel ever killed anybody in the comics. The serial was a different story.
The site "Comic Book Plus" ( where I got this story ) complains about Billy Batson appearing in blackface, something which is not considered to be acceptable today. Now, that's something that I don't think Superman ever did.
SHAZAM by Chip Kidd: