GB MP5 7.62x25 A custom built MP5 chambered in 7.62x25mm Tokarev. It uses PPSh 35-round magazines. It has an extended, permanently attached flash hider to maintain non-SBR length. GB stands for GhillieBear, a well-known HK gunsmith on the HKPro forums. He no longer builds these so the 12 or so he built are all that’s out there. This is not a simple build, the barrels were specifically made for it.