He's 21 and mature enough to go to prison. He can be paroled to a half-way house or shelter. He's an adult. He's not your problem. It's your girlfriend who needs to choose between you and her son. Damn, I feel like Dear Abbey

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Some years back I allowed a niece to stay with us until she got on her feet after drug rehab. She was also on probation for a drug charge. The probation officer met with me regarding firearms in the home. I advised her my firearms are all under lock and key and invited her to come to my home and see for herself. She didn't care to inspect. She did several home visits for probation and never asked about the guns again. On a side note, my niece relapsed. One evening she came home drunk and high and went ballistic when my wife asked her about it. Police had to remove her as she threatened to harm herself. She went back to rehab for 90 days and then to jail for 6 months for violating probation for the fourth time. That was in 2010. I never saw her again. She had been doing so well. I had her enrolled in college and she seemed to be gaining ground. I've heard she's a heavy drug and alcohol user and living in a nearby town. You can never tell who will re-offend. You can't help someone who can't help themselves. Only so much you can do.