Using the fine blade of a grinder, grind the pork. After lubricating stuffer or stuffing attachment with shortening, load casing onto attachment, clipping end with a clothespin. Stuff meat into casings, trying to avoid air pockets. After stuffing is finished lay out on counter and tie off end. Pinch and twist to form 4-inch sausages. Wrap in parchment paper and refrigerate for 2 to 3 hours. Store in refrigerator for use within 2 to 3 days or freeze for up to 3 months. If freezing, wrap in aluminum foil. If using immediately, saute over medium heat in a heavy saute pan with 1/4-inch of water. Bring water to boil, put on lid and cook for 10 minutes. Remove lid and continue cooking over medium heat, turning every 2 to 3 minutes until golden brown. Sausage should reach an internal temperature of 150 to 156 degrees F.