Sir Joseph Whitworth is quite the famous name in engineering circles, credited with the development of such things as Whitworth threading (the first standardized thread pattern) and engineer’s blue. When he decided to make a rifle, he decided that he could make flat surfaces more precisely than round ones, and chose to design a rifle with a hexagonal bore and mechanically fitted bullets.
Video: [15:19]
https://youtu.be/Hi-S_horZGk?si=
Ian makes a correction to the original video: [7:18]
https://youtu.be/cUd2RQGfL7E?si=
Do we use round bullets today because he was wrong about his assumptions, or was he correct, but round is easier and cheaper to manufacture?