Has anyone installed a Wyatt's CFE-9 Extended Magazine box? It states the receiver, bolt stop, and ejection port have to be altered. I am tracking the reciver and bolt stop mods; what are the ejection port modification requirements, I have not seen or read about this. I am building a 375 RUM and am trying to decide whether or not to do a center fed (CFE-9) or install a longer staggered fed box (MBE-3). Thanks in advance for any assistance.