In the act of shooting?

[The R]

A1 rebounds the ball and begins the habitual motion to shoot. B1 grabs A1's arm. You have a whistle at this point for a foul. A1 gives up on that attempt then makes a legal step through move to the basket and makes a bank shot.


How do you handle this play?

Note: You deem A1 to be in the act of shooting before his arm is grabbed. The step through move was a separate act of shooting.