i was looking up some stuff on that class of weapon last night, technically it's clasified as a handgun. One stabilizing brace called for a hole to be drilled at the back of the reciever for the brace to be secured with a bolt.
I just wonder how legal that is, wouldn't that be turning it into a short barreled weapon?
It depends on the device. To be safe, you should only buy a device that's classified by the ATF (with a letter to the manufacturer) as a non-stock. Interestingly, if it's classified as a non-stock, the ATF has no authority with regard to how you use it, to include shouldering it, and the ATF has admitted as much. For example, if you chose to touch your 1911 to your shoulder while you fired it, this wouldn't convert it into an SBR . Same for these brace equipped "handgun."