Ball hits mitt then bat

[rcaverly]

2-21-4 . . . Follow-through interference is when the bat hits the catcher after the batter has swung at a pitch and hinders action at home plate or the catcher’s attempt to play on a runner.

7-3-5 . . . Interfere with the catcher's fielding or throwing by:
c. making any other movement, including follow-through interference, which hinders actions at home plate or the catcher's attempt to play on a runner...

PENALTY: When there are two outs, the batter is out. When there are not two outs and the runner is advancing to home plate, if the runner is tagged out, the ball remains live and interfer¬ence is ignored. Otherwise, the ball is dead and the runner is called out. When an attempt to put out a runner at any other base is unsuccessful, the ¬batter is out and all runners must return to bases occupied at the time of the pitch. If the pitch is a third strike and in the umpire's judgment interference prevents a possible double play (additional outs), two may be ruled out (8-4-2g).

7.3.5 SITUATION F:
With R1 on third, one out and two strikes on B3, B3 swings at and misses the pitch. The ball bounces off F2’s glove into the air, where it is hit by B3’s follow-through. The ball rolls to the back stop. B3 reaches first base safely and R1 scores.
RULING: The ball is dead immediately. B3 is out for interference and R1 returns to third base. A batter is entitled to an uninterrupted opportunity to hit the ball, just as the catcher is entitled to an uninterrupted opportunity to field the ball. Once the batter swings, he is responsible for his follow-through.