I know the Mammoth is pretty much extinct but I just bought one and had it drilled rico.  I was a little worried about it as I haven't had much luck with pin down balls lately, mainly my cell.  Anyway.. I could not be happier with the ball.. smooth as silk.. super predictable, still has backend, covers some boards and still has some recovery if I swing a bit too wide .. and this was on a reverse block where everyone else was hitting the 10 pin on the first shot if they went too wide.., and did I mention it hits like a truck.. was alittle worried when the ball hit the pocket because it was getting to the pocket at an angle I'm not used to .. but no worries.. it smashed the rack..

I'm glad I rico'd ..
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16-17 mph
350-475 rpm
PAP 5 1/2 x 3/8 up
High Game 300 x 3
High Series 782
Book Average 215 / 205
PBA Xperience ave 180
years bowling 22