commercial propellants that suited the cartridge. Even the standard slow burning powder of the time IMR4350 which was used in the Weatherby line of cartridges was too fast to take advantage of the case capacity of the .30-378 Weatherby cartridge. The result was that performance advantage that was created by the volume of the .30-378 Weatherby was minimal over the competing .300 Weatherby Magnum cartridge, which had been introduced 25 years earlier. However, when launching bullets which are extremely light for caliber as the Redstone Arsenal contract specified, required the use of relatively faster propellants. However, the hunting public and target shooters used 150 gr and heavier bullets, which require slower burning powders due to the extreme overbore nature of the cartridge. SAAMI compliant .30-378 Weatherby Magnum cartridge schematic: All dimensions in inches [millimeters]. SAAMI recommends a 6 groove barrel with a twist rate of . The recommended bore diameter is and groove diameter is with each groove having an arc width of . Performance The .30-378 Weatherby Magnum is one of the most accurate rifle cartridges. The cartridge held the world record for accuracy at for over thirty years. Given factory ammunition, Weatherby guarantees 1.5 MOA accuracy from their Weatherby Mark V action rifles and sub-MOA (.99 MOA or better) accuracy from their Range Certified line of rifles and Vanguard rifle lines. Careful handloading – checking for bullet jacket concentricity, weighing of brass and bullets, uniformity of case length and overall cartridge length, choice of components, seating of bullet – can all increase the accuracy of the cartridge. The .30-378 Weatherby Magnum is a long range cartridge. It is the most powerful - in terms of energy - .30 caliber production cartridge available. It is also the flattest-shooting .30 caliber factory ammunition available. Dependent on the ammunition chosen the cartridge has a maximum point blank range of over . The cartridge retains enough energy for deer-sized game at distances over , and has enough retained energy for elk and moose-sized game at a distance of over . Sporting usage Like all Weatherby rifle cartridges the .30-378 Weatherby was designed to be a high performance hunting cartridge. When released to the public, it is intended for the hunting of all the big game species of North America, Asia and Africa, save dangerous game. Since this is a small bore caliber, hunting with the .30-378 Weatherby Magnum should be restricted to