I'm trying to outfit myself with a couple of these before the election. Most of my experience is with old single shot rifles. I'm thinking of getting two of them for 223, being I already have alot of that on hand. I'd like to have one for .308. I want to aquire at least the lower receivers before the election, and enough parts to build one for .223. I have enough money to swing this, the problem is I don't have an education on this yet. So I'd like to build a .223 one right away. I live in California. So my questions are: 1. When buying a lower receiver, will they take any magazine meant for any AR15, or do you need to match brand to brand? 2. I read rock river makes a receiver or chamber called "Wylde", what model is that? Is it the lower, or upper? 3. I also read that you can change calibers by swapping uppers. That doesnt sound right, because it seems the width of magazines would vary and they wouldnt fit in lower? 4. If a lower is stamped 7.62, does that mean it will shoot .308 without any problems? I realize these questions may sound stupid, but just try to help me and tolerate it for a while please. I need at least get the parts soon that could be stopped from ordering or become more complicated after the election. So any advice on this would be appreciated.