This is the 300 Weatherby necked to 6.5mm with no other changes, which makes it the same as the 6.5/300 Weatherby-Wright Magnum that was first listed in the 1962 edition of P.O. Ackley’s Handbook for Shooters and Reloaders. It was developed by Lt. Col Paul Wright of Silver City NM, who was a 1,000 yards bench rest shooter that was looking for a very flat shooting cartridge with manageable recoil. The development of very slow burning powders as well as a wide selection of high quality bullets has led to resurgence in interest in the 6.5mm’s in the last few years with the likes of the 6.5/284, 26 Nosler as well as the 6.5 Creedmoor.