Basically, my character is below the legal age to buy a gun (he's seventeen) and so accquires one illegally through an older friend. After a blowout with his father, he packs his bags and leaves home, but is forced to threaten his father with the gun in order to get out of the house. His father then calls the cops on him.
My question being: what punishment would the character receive for possessing a gun underage, if any? And would the sentence be made harsher since he threatened his father with it? I had in mind a short stint in a young offender's institute or prison, but suspect the real punishment does not lend itself so well to potential character development.
To be specific, the character lives in Forth Worth, Texas, and the story is set in the early 90's.