I'd like to hear some opinions on the legalities of a AR-15 pistol in 9mm or 223. Specifically, can you legally shoulder-fire an AR-15 pistol? I've seen foam covers for the extension tube, and there are products like the Endine hydraulic buffer that reduce felt recoil. I know that adding a recoil pad or buttplate of any type would be completely illegal, but the recoil of an AR-15 isn't so bad that a foam-covered extension tube would be unmanageable, especially with an Endine installed. As long as there isn't a buttstock and it's a registered pistol, can use be regulated? Is there an overall lenght limit that keeps a full-length carbine or even A2 extension tube from being used? As a disclaimer, this is a completely hypothetical question and in no way reflects a request for information on illegal actions. I take pride in following the letter of the law. I do not at this time own an AR-15 pistol of any type. Thanks!