Go to brpguns.com and look at the website. I don't believe you can reconfigure the receiver into different guns. It will be what it is built as. I think he called it a takedown to keep ATF happy that he wasn't modifying the original receiver. He had a heck of a piece at KCR that used an MG34 grip assembly. It is still, however, an open bolt tube gun. For the price you can get a Sten (low 4K) and an M11/9 (3K). With the Lage upper and other upcoming stuff the M11/9 is a very good start in Class III.