In a bowl mix together the spice blend ingredients. Take 2 tablespoons out for the marinade injection (if doing). Reserve another 1/2 cup for later use after pork is pulled. Remaining dry rub is for Step 3.
Using paper towels, dry off the pork shoulder. Trim fat cap on pork shoulder down to 1/4-inch thickness, and trim away any visible purple or red spots (those are glands and they will have an undesirable, chewy texture).
Rub spice blend on all sides of the pork shoulder. Wrap the pork in plastic wrap, or in a covered container, and refrigerate for at least 8 hours.
An hour before smoking, unwrap the pork shoulder and let it come to room temperature. Mix together the marinade injection mixture (if doing). Inject pork all over with the marinade (optional).
Preheat smoker to 225°F. Prep your wood chips or pellets as per manufacturer's instructions.
Place the unwrapped meat directly on the clean grill rack of the smoker.
After 4 hours, spritz all sides of pork with apple juice. Continue cooking, spritzing the meat every 30 minutes, until the pork internal temp reaches 165°F.
Remove meat from smoker and wrap in butcher paper or a double layer of aluminum foil. Place back in smoker and continue smoking it wrapped until it reaches an internal temp of 190°F (for slicing) or 205°F (for pulling).
After meat reaches desired internal temperature, transfer wrapped meat from smoker to an EMPTY cooler (lined with a towel to assist with lifting it out) Allow wrapped meat to rest for 1 hour, covered.
Lift from cooler, remove paper or foil wrap and discard. Place smoked pork shoulder carefully on a baking sheet or tray. Remove pork bone and discard. The meat should fall apart easily. Use gloves or BBQ claws to pull and shred the pork.
Sprinkle liberally with remaining 1/2 cup sweet pork dry rub spices (to your liking). Feel free to add more apple juice or your favorite BBQ sauce.
Substitute with Smoked Paprika for a more smokey flavor.
General RuleSmoke 90 minutes per pound. After it's reached an internal temperature of 205°F remove from smoker. Set it, still wrapped, in a cooler to rest for 1 additional hour covered, before pulling the pork.