Heres the skinny on corked bats...
A 3/8 inch diameter hole, or bigger if desired, is drilled from the barrel end down thru the sweet spot, roughly 10 inches. Cork, pieces of rubber balls, or whatever is packed into the hole, sealed with wood putty and sanded down as to not show. This is to presumably make the bat lighter and add a substance that allows the ball to come off the bat quicker and travel farther
In truth it does neither!
Studies have been done on corked bats and it was concluded that the process does not alter the speed and distance of a struck ball. In fact, it weakens the bat and makes it prone to shatter as did Sammy's.
Bat corking is psychological. Baseball palyers are the most superstitions athletes around. Hell, some rub chicken bones on thier bats, a process called, yes, "BONEING". Some will wear the same skivies for a week if they think its what got them out of a slump.
Peace out
BD