Joseph Whitworth was the foremost manufacturer of machine tools of his time. That is why he was approached by the War Office to provide assistance with regards to the design of appropriate machinery for the manufacure of the Enfield rifle.
Not content with considering the machinery for the manufacture of the rifle, he determined that a more appropriate course of action would be to establish that the proposed rifle was of optimum design before considering its mass production.
It is from his subsequent experiments that his .45 cal hexagonaly bored rifle evolved. It should be noted that the polygonal rifling was not an original idea, having been previously considered by that great engineer, I.K.Brunel.
David