This is my recent acquisition, also from "no name" maker, with British proof marks on both the barrel and receiver. One of the marks reads .375 EX., which led me to believe that it was a converted .375 Nitro Express. However, the load it was proofed for is clearly not that of a .375 Nitro Express, and it is marked ".375 H&H Magnum" elsewhere, and accepts .375 H&H cartridges.