That's probably true with most bullet designs, but there are some "collar button" bullets that are slightly lighter.
Lyman #427130
147 gr, 0.460"
That's about the same as it would be for a round ball, but some of the collar button bullets do not have the rounded nose and are more flat on top, so they will weigh less. Or you could hollow point it to get it to weigh less. Or you could go with a hollow base design and create basically a skirt around the base of the bullet.
The main advantage of round balls is that it doesn't matter if your bullet *tumbles*.