From what I remember reading it is because the magazine is not in the grip, and on a pistol a detachable magazine has to be inserted into the grip to be legal here. Since this state defines a fixed magazine as one that requires a tool to remove, installing a bullet button means it no longer is capable of accepting a detachable magazine outside of the grip and thus is legal...or so the current popular interpretation of the law goes.
If I am wrong please correct me. I am by no means an expert on pistol ARs.
There is a flow chart showing what is and is not allowed on pistol ARs somewhere here. Do a search for it and you will learn all you need to know. Discussing it here is kind of hijacking the thread, since people want to see pictures here...and learn about the law there. Not trying to be rude, just trying to avoid being flamed by other members.
Last edited by tacticalcity; 03-29-2009 at 1:03 AM..