Hi sketch
"What would happen if a hedge fund tried to corner the silver market instead of cocoa market?"
You just have to look back to the Hunt Brothers. They made legal purchases of silver on the US exchange and requested delivery. The rules changed imediately to make it impossible to go long and the regulators allowed the exchange to not only change the rules(and the contracts) but they made brought charges against the Hunts. Recall that all the Hunts did was buy what was offered and ask for it to be delivered. The Hunts made a perfectly legal request and in keeping with the rules and contracts in effect at the time.
The crimex is a tool for manipulation. When their con game goes up in smoke it will be the longs that get screwed and the criminals will go free... again. And the price of silver will go ballistic!