Strange...the drillers I've talked to all say that you're actually better off if you can drill through the pin. They tell me that it's the "interface" between the pin and the shell that is at the root of most pin-related cracks, so by drilling through the pin, you avoid this problem altogether.
And yes, I've drilled several balls through the pin, and I've never had a problem with cracking.
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...formerly "The Curse of Dusty," and "Poöter Boöf" before that...