hey guys, noob here but not to the gun world. very close to buying a mke mp5 clone long barrel. problem is that it has a 10 round mag. can a 30 round mag fit or what do I have to do to make it fit properly without it falling out. thanks. oh, and where can I find a full US spec 922r kit so I dont get in troule. Im living in Ft. Lauderdale, FL. A3 stocks not allowed?