here is a brine recipe, should help make your tough birds a little more tender.
16 cups of water
3/4 cup kosher salt
2/3 cup sugar
3/4 cup soy sauce
1 teaspoon each of dried tarragon, thyme, black pepper
1/4 cup Italian salad dressing
Start by boiling 4 cups of water and then adding the salt and sugar, so that it will dissolve easier. Then add the spices to the hot liquid so that the flavors are extracted. Cool the brine solution with the remaining 12 cups of cold water.
Place the brine solution into a non-reactive container and immerse the chicken in the brine, weighting it down if necessary. Place the container into the refrigerator and leave for 10 hours. You can also brine the chicken in an ice chest, by pouring the brine solution into the ice chest, immersing the chicken and weighting down.
Upon completion of the brining time remove the chicken from the brine and wash twice for at least 30 seconds in fresh water. Dry the chicken with paper towels after this you can either freeze or cook.