Im thinking about doing a AR-15 build. I am looking for a receiver to buy and start the project. Before I do I seem to recall reading of a receiver that could have the magazine well portion changed out so as to allow for AK-47 mags to be used for those who had a 7.62 X 39 chambered upper. I have tried a number of google searches and cant find anything on such a receiver. Does anyone know if such a reciever exist? If so what is the brand?