Dirty magazines

An army major called his wife to tell her that he would be late home because dirty magazines had been found in the barracks, and the soldiers responsible were facing serious disciplinary action.

"The punishment sounds a little harsh" she said. "After all, most of the soldiers have pictures of women on the walls of their quarters".

"No, honey," he explained patiently.

Spoiler:

"Dirty magazines means the clips from their rifles had not been cleaned properly!"