i don't think you can make a generalization about where the mass bias is on a ball that is not marked. the mass bias will depend on the shape of the weight block and its position within the bowling ball.
i have several hammer wheels. the mass bias is marked with a "hot" spot, but the CG can be either to the right or left of a line between the pin and hot spot. that's because the core is leaning slightly to one side of the ball.
go to visionary's website and look at the charcoal executioner core. the mass bias is 11 1/4 inches from the pin. i think you'll see what i mean.
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That which does not kill me makes me stronger . . .