Mix the bison, rice, onion, green pepper, and milk. Season with salt and pepper. Form into 1-1/2 inch balls. Place in a 9x13 inch pan. Cover with aluminum foil. Bake at 325 degrees F for 30 minutes.
Mix the soup and milk.
Remove foil and drain the liquid from the meatballs. Cover with the soup and milk mixture. Bake for another 30 minutes.