Rapper Obie Trice is going 1 for 2 in his Michigan gun case -- avoiding a more serious charge for shooting a guy, but the D.A.'s Office isn't letting him off the hook completely.
The former Shady Records MC will NOT be charged with felony aggravated assault after a gun went off and struck his girlfriend's 18-year-old son during a brouhaha they all got into back in December.
Oakland County Chief Assistant D.A. Paul T. Walton tells TMZ there wasn't enough evidence to bring that specific charge against Obie -- who insists the gun went off by accident, and he only had it out while acting in self-defense.
He is, however, going to be charged with misdemeanor possession of an unregistered firearm -- which could land him in jail for 90 days, if convicted.
TMZ broke the story ... Obie -- forever remembered for his opening line to Eminem's "Without Me" -- was arrested after getting into a physical altercation with his girlfriend, which allegedly turned into a tussle with her son.
At some point, cops say Obie went to his car to retrieve a pistol, and while the kid tried to get it away from him -- a bullet was fired and went through the kid's groin. Sounds like he's gonna be okay ... he drove himself to the hospital that night.
Obie is set to be arraigned later this week on the gun possession charge.