When I was a prosecutor, we had a trend of cases where criminals were using airsoft or BB guns to commit offenses, as it had become known in the local criminal world that the three year sentence for use of a firearm in the commission of an offense meant that it had to be a functional firearm. Using a non-firearm meant if they got caught, they dodged the three year bonus on their sentence, and also could apply for some of the diversion programs which weren't eligible to anyone convicted for use of a firearm. Don't know what stopped that trend, but it only lasted 2-3 years.
Like Hawk's example, I was once in a gun store on the edge of a bad part of town, as they were the only one locally that had a Hogue grip I wanted in stock. As I was at the counter browsing, a kid came in and had a handgun in a case he wanted ammo for. It was an old handgun, can't recall what it was. Employee said they didn't stock ammo for it, as it was an unusual caliber, but indicated they could order ammo for him, and it would take 7-10 days to get it in. The kid then asked what they would give him in trade for the old gun, as he needed something that could shoot that day. Employee said they needed to check on the value online, and took the old gun to a computer. Amazingly enough, the kid stuck around while they "checked value" on the old gun. Yep, they were calling the police. Yep, it was a stolen gun. Yep, the kid was arrested for possession of stolen property.