We manufacture and support the precision digital scales that the USBC uses to check every ball at the tournament, and have done so for several years now. USBC goes to a great deal of trouble each year to make the ball screening rigorous. Every ball is screened before it can be taken into the tournament.
NCAA tournaments and some international tournaments also screen equipment with our scales.
On average, out of every 1000 balls checked, 50 are found to be very close to or over the regulated weight limits. Of those 50, 25 are passed after a more careful screening. Of the remaining 25, half are so out-of-round that they 'lean' in the scale, giving an exaggerated reading in the scale. The remaining 10 or so are really out-of-spec, and must be drilled to be legal.
Regarding someone who passes one day, but gets caught the second day, remember that the screening process is designed to be fast, and the screeners don't carefully measure each ball to precisely find grip centers they estimate it on the fly. If your equipment is close to the limit then the screener could easily pass you one day, but catch you the second day because the grip center was estimated a bit differently.
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Dr. Douglas G. Frank, President
Precision Analytical Instruments, Inc.
www.ToolsForAnalysis.com
