The problem with a conical projectile is that you no longer are able to add backspin (lift), so the flight will be parabolic. The only other way to flatten out the parabola is to increase velocity, and increasing velocity increases risk.
Yes, there is less drag on a cone than a sphere, but at the velocities we play at, I don't think it's a good idea. There isn't enough energy to spin the projectile (rifling) and if there is, you're in the realm of air guns/pellet guns, which can kill people.
These are an example of finned bb's