Illegal Bat

[akalsey]

If the umpires didn't notice and no one complained his first AB, then how does anyone know that he used it the first time? This sounds a bit odd.

There's no rule in OBR that says a bat not meeting certain specifications results in an out. Take the bat out of the game and warn both teams that further use of illegal bats will result in ejections.

If the umpire inspected the bats prior to the game and someone hid this bat and pulled it out after the inspections, then perhaps eject the player for unsportsmanlike conduct.