UFC Star Joe Riggs -- My Gunshot Wound Healed ... Check Out My New Scars

UFC fighter Joe Riggs might be part mutant -- 'cause check out how well his gunshot wounds healed up in just THREE SHORT MONTHS!!

As we previously reported, Riggs was cleaning his pistol back in July when it accidentally fired -- sending a bullet ripping through his hand and thigh. It was bloody ... and could've been career-ending.

But as you can see in the pics, everything seemed to heal nicely -- and Joe just announced that he's booked his very first UFC fight since the incident.

The fight is set for Dec. 13th -- and Riggs is all set to take on Ben Saunders ... who, to our knowledge, has zero gunshot wounds.

We included the original bloody gunshot pictures below ... but be warned, they're pretty gnarly.