I know "FWUMP" is an undignified sound effect, I can't help it, it's just the sound they make. :P
Undignified but certainly stomach clenching when you imagine it.
Not one I want to hear in person.
Don't worry: The sound makes it brutally clear whats happening. Brutally !
In related news, pistols actually do go "bang." How trite of them. :P