HK91/G3 Receiver Flat [BS3-A5] HK91/G3 Receiver Flat [BS3-A5] These flats are made on original HK tooling by Gewehr Werks. This is the same HK tooling that was imported by ORF. These are the nicest, easiest to build flats ever available in the U.S. Dimensionally perfect with crisp stamping's and flattened rails. No FFL required. This flat can be used to complete all HK91, HK51, G3, G3K and Cetme builds $59.99 This image has been resized. Click this bar to view the full image. The original image is sized %1%2 and weights %3.