Allow turkey to completely thaw (about 5 days).
Fill a cooler that will fit the turkey half way full of cool tap water.
In a pot combine 1 cup of salt, 1 cup of white sugar, 4 cups of water, McCormick poultry seasoning, and a generous amount of BBQ rub. Heat and allow to dissolve completely.
Combine the brining mixture with the water in the cooler and add ice. Place the turkey in the cooler and add more ice to ensure the turkey stays cold.
After 12 hours flip the turkey over in the cooler, add ice as needed. Pull turkey out of the brine 2 hours before cook time in order to allow it to warm to room temperature.
After brining the turkey for up to 24 hours rinse the turkey and remove the neck and giblets
In a sauce pan combine a full stick of butter, a table spoon of salt, a table spoon of white sugar, and 2 cups of chicken stock. Melt the ingredients together. Once it is well mixed inject the turkey with the mixture. Allow to sit for 30 minutes at room temperature.
Pour left over injection mix over the turkey for the seasonings to stick. Use salt, pepper, and poultry seasoning to dust the out side of the turkey.
Cook for 8-9 hours at 225°F, spritzing ever hour. Pull the turkey off the grill when internal temperature is 165°F and cover with tin foil to let it rest.
After at least 30 minutes of resting serve with your favorite sides.