378 Weatherby - question


How did Roy make the first cartridges in this caliber? Did he modify 416 Rigby cases adding them a belt or were the first ones made by Norma? And what about the 224 ?

The other Weatherby cartridges were made simply modifying other cartridges , for example the 6 mm Ackley Express for the 240 Weatherby magnum ( or the 240 H&H magnum belted) , the 300 H&H / 375 H&H for the medium calibers and the 378 Weatherby for the biggest ones


According to my information the .378 was an original design case, not a reformed 416 or 375 H&H. Vic


My notes show that it was developed by Roy Weatherby and first used by him on an African hunt in 1953.
It was a new design, the best that I can find.


Thanks , I know it was a new design , anyway , except for the belt and caliber ,its outside dimensions are almost identical to the 416 rigby , so I wondered if Roy made some prototypes himself altering a rigby case ( necking down , belt swaging and fireforming) or if he gave Norma guys a drawing only