Not Guilty In Federal Gun Case

11:28 AM PT -- YoungBoy's attorney, Andre Belanger, tells TMZ the rapper put his head down and started to cry when the verdict was read ... it's been a stressful and emotional situation for him. In walking out of the courtroom, Belanger tells us YB exclaimed, "I was never guilty of this."

NBA YoungBoy has just been found not guilty in his federal gun case.

The verdict, confirmed by both NBA's lawyer Andre Belanger and the U.S. Attorney's Office comes after a 3-day trial ... the jury found him not guilty of a charge of illegal firearms possession over a loaded handgun found in his car last year.

As we reported, LAPD and the feds attempted to pull over a vehicle the rapper was in last March on…