I'm very much interested in getting an AR10. Although I consider myself rather experienced with AR15s, having owned several over the years, I'm extremely clueless when it comes to the AR10 platform. I've seen that there are some from CMMG, DPMS, Rock River, Armalite etc... And as usual, I want to get one without breaking the bank. So who offers the best bang for the buck? I like the idea of piecing it together (as I have done with my ar15s) so that I can customize the rifle to my liking, but I'm clueless as to who's uppers are interchangeable with others... Or are they all proprietary? On another note, Let's say I wanted to free float a barrel using a MI rail, would an AR15 rail be compatible or no? And not to add frustration, but I also own a FAL, therefore I have access to FAL magazines, and I was informed that certain 308 ARs accept FAL magazines. Are these reliable? Or would I be better off buying a lower that accepts the 308 Pmags?