I believe this is the idea: Consider two .430" diameter cast bullets, one is a Keith with a .270" meplat and .430" shoulder, the other is an LBT flat point round nose with a .340" meplat. Despite the lack of a full diameter shoulder, the LBT hits harder and makes a bigger hole.

The second bullet makes a bigger hole than the first:

[Linked Image]

Note: Photo lifted from elsewhere on the 'fire.