I don't think there's ever been an arrest but the argument would be one of intent. Why own a collapsable stock unless one was going to use it?

Personally I wouldn't worry about it too much but wouldn't buy one just to fondle - I have better things to fondle [:D]. The ATF rarely get out in the middle of the night - they pretty much nab you in the middle of the day.

I've wanted to have one just to "have one", but figured I'd be to tempted to put the damn thing on just to see how cool it'd look. So I figured best thing to do is just not buy one!

Kinda sucks too. The only way my petite wife can even shoot a 16" AR is with a bipod because the stock is to long and she has a hard time getting her hands on the hand gaurds. It's either that or she has to hold the mag, which I'm not to fond of. So it's the bi-pod on a bench for her.