Start the Traeger according to manufacturer's instructions.
Once it starts smoking, set the temperature to 180°F and let come to temperature (about 10 minutes).
Prep the pork shoulder before placing on the Traeger
Let the pork shoulder sit out at room temperature for about 30 minutes before you prep it to start smoking.
Rub the pork shoulder down with yellow mustard until well coated.
Sprinkle the dry rub all over all sides of the pork shoulder, patting into the mustard to help it stick on.
If needed, tie the shoulder together with cooking twine. This is especially helpful when using a boneless pork shoulder.
If using an injection marinade, do your injection now, following a patchwork pattern across the pork shoulder.
Set the pork shoulder on the Traeger and start cooking.
Put some apple juice into a spray bottle, and while smoking the pork shoulder at 180°F, spritz every 30 minutes or so with the juice.
Smoke the pork shoulder
Smoke at 180°F for ~12 hours, until the meat reaches an internal temperature of at least 160°F, up to 180°F.
Raise the temperature on the Trager to 225°F.
Wrap the pork shoulder in foil, and pour a little apple juice into the bottom of the foil wrap.
Let the pork shoulder continue smoke until the internal temperature reaches 205°F, about 4 hours.
Let the pork shoulder rest
Pull the pork shoulder off the Trager, and reserve the juices.
Re-seal the foil around the pork shoulder, wrap in towels, and place somewhere that the temperature will be relatively insulated for several hours (inside a cooler, inside the oven with it off, etc).
Let sit for 1-3 hours.
Shred, season, serve
Put the shoulder into a large pan, and shred.
Add reserved juices, and additional dry rub to taste.
Notes
Serve with Carolina BBQ Sauce. You can find a suggested recipe here.