In a large bowl, cream together the shortening, peanut butter, brown sugar, and 1 cup white sugar until smooth. Beat in the eggs one at a time, and stir in the milk and vanilla. Combine the flour, baking soda, and salt; stir into the peanut butter mixture until well blended. Shape tablespoonfuls of dough into balls, and roll in remaining white sugar. Place cookies 2 inches apart on the prepared cookie sheets.