ADD meat to slow cooker. Top with Simmer Sauce; cover. Cook on LOW 8 to 10 hours (or on HIGH 6 to 8 hours).
30 MIN. BEFORE SERVING transfer meat to cutting board. Let stand 10 min. to cool slightly and seal in the juices. Pull meat into shreds with 2 forks.
REMOVE liquid with ladle from slow cooker; set aside.
RETURN meat to slow cooker; stir in Finishing Sauce. If desired, add some of the reserved liquid to desired consistency. Increase heat to HIGH; cook, covered, 15 min. Serve in buns.