You seem to be actually interested in physics, please take a course! There's lots of learning facilities on the net. But stop asking AI as if it knew anything more than how to generate convincing sounding bullshit. So get some real knowledge and lighten up on those taking the time to try and answer you!
Oh, my attempt: the force on the gun barrels as the bullets turn 180 degrees around will try and push the gun in the original direction of that the bullets were fired in. The gun will be act like it's being ripped out of your hands and unless you hold tight, it will fly away. Holding tight will ofc counteract the force of the bullets impacting your chest.
To turn 180 degrees without some force being involved makes as little sense as reversing direction with a magic portal ala the
Portal video game. Now if you posit that you have a portal that you shoot into, and the back-end of the portal points back at you so the bullets reverse direction without use of energy ... yeah, you've done it 
But your post was cool in that it did remind me of how fun it was to read about Cartoon Physics
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