actually, the whole gun is legal! its a silly law when you really start to read it. but yeah, basically if my mag needs a tool to be released, then i can have all the parts that would otherwise make this an assault weapon according the penal code. these parts are known as "evil features" and are the collapsible stock, rear and forward pistol grips, grenade launcher, flash suppressor, etc.
if my mag could be released with my finger, then i couldnt have any of these parts and essentially could not own an M4 and I would have to get a regular rifle like a Kel-tec
Does that kinda make sense?