Lil Flip -- I'm LICENSED to Pack Heat ... Drug & Guns Arrest Was Bogus

Lil Flip is vowing to fight his recent drug and gun arrest because he claims he can prove the assault rifle found in his car is 100% legal ... TMZ has learned.

The rapper was busted Christmas night in Louisiana when a cop pulled him over for speeding ... and then allegedly found ganja and an AR-15 rifle in the car. Flip was booked for possession of marijuana and possession of a firearm in the presence of drugs.

Flip tells TMZ he has a valid license to carry the gun -- which he claims is not automatic firing -- and says he needs to carry it because he's an entertainer who's been shot before.

Flip -- real name Wesley Eric Weston-- gave TMZ a photo of his Texas concealed handgun license ... which he says is also valid in 22 other states, including Louisiana.

As for the weed ... Flip claims they were "Black and Mild" wine flavored cigars and clove cigarettes, and says he is "not one of those rappers who would carry drugs on me. I know better."