'Dallas' Star Jack Scalia -- Charged in LAX Gun Bust

Fact: playing dumb about a gun in your carry-on ain't much of an excuse -- something "Dallas" star Jack Scalia learned the hard way ... 'cause he's been slapped with 2 weapons charges, TMZ has learned.

We broke the story ... Scalia was busted at LAX in October when TSA agents found an unloaded 9mm Glock and a novelty police badge in his bag. He claimed the badge was a gift from Rudy Giuliani. As for the gun, Scalia said he had no clue how it got in there.

But the L.A. City Attorney didn't buy it and charged Scalia with two misdemeanor counts -- one for carrying a concealed firearm and another for taking a prohibited weapon through the sterile area at the airport.

If convicted, Scalia could face up to one and a half years in jail and $2,000 in fines.