Barbecued Turkey Sandwiches

Ingredients

• 2 celery ribs, chopped
• 1/2 cup chopped onion
• 1/4 cup chopped green pepper
• 2/3 cup butter, softened and divided
• 1/2 cup ketchup
• 1/4 cup packed brown sugar
• 3 tablespoons Worcestershire sauce
• 1-1/2 teaspoons chili powder
• 1 teaspoon salt
• 1/8 teaspoon pepper
• 1/8 teaspoon hot pepper sauce
• 4 cups shredded cooked turkey
• 8 hamburger buns, split and toasted