My 1990 Vollmer MP5 was built with a German MP5 barrel. Back in the very early days of the internet message boards, there was a discussion of Vollmer MP5 barrels. Fred posted that he sometimes used Turkish barrels (which some poeple didn't like), and Fred posted that he never claimed his barrels were always German. I didn't think three lug attachments were widely used, there were enough problems with HK contract barrels and out of spec lugs that wouldn't allow adding the flash suppressor or sound suppressors. Back in the day, builders used whatever they could get their hands on, sometimes German, sometimes HK contract, sometimes you made what you couldn't get.