Caliber dictates bullet shape?
This may be the best place to ask this question. Why is it that certain calibers have very distinct bullet shapes, and no matter the loading or the manufacturer, the bullet shapes do not vary that much? For example, .223 is always pointy, .17 HMR even pointy-er. 30-30 is always rounded or blunt tipped. .308 are pointy. Most .22 LR has some flavor of "sealing rings" around the base of the bullet, and you never see really pointy .22's.
Is this functional, or tradition? Why don't people try different bullet types in different rounds? If .17 HMR's fly true with needle-points, why not .22's? How would a 30-30 work with a .308 boattail, or vice-versa?