Appleton-based Mills Fleet Farm has plans to open five new stores by October and seven more next year. The company hopes to have 70 operations going in the next four or five years. Right now, the focus is on a new store in Grafton. The company is also planning to replace a West Bend location with a larger store. The Grafton store would be the 43rd Mills Fleet Farm location. The retailer sells outdoor gear, tools, farm equipment and clothing. Much of its growth has come since the chain was sold to a private-equity firm just over two years ago.