Put meat in crock pot. Cook on high for 1 hour then turn to low and cook for 4 hours until tender. Drain cooking liquid, reserving 3/4 cup.

Cool beef; shred and return to crock pot. Add cabbage, barbecue sauce, ketchup, Worcestershire sauce, horseradish ( optional), mustard and reserved cooking liquid. Cover and simmer for 1 to 2 hours. Serve warm with in buns.