Paging Aerohead -- [found it, see below] I've looked for and can't find an illustration that has been posted here. IIRC it was from a naval architect, about torpedoes. It employed a profile that consisted of the straight line of the forebody, a simple curve transition, and a straight line for a terminating cone. Again IIRC, it transitioned to a straight cone around 22°
here is an irrelevant example:
Depending on your needs a more easily built shape might have a place. Optimum is optimum. The perfect is the enemy of the good.