I highly recommend you visit www.Calguns.net
Visit the centerfire rifles section and look at the stickies at the top of the forum.
Basically I'll sum it up as this, so long as you have a bullet button, and the overall length with the stock fully collapsed is over 30" (iirc), collapse-able stocks on your AR are fine. Also you may not have any magazine with a capacity greater than 10 rounds in ANY bullet button magazine locked rifle. Note-able exceptions are registered Assualt Weapons (AWs) and (evil) featureless rifles.