I'm really surprised so many in here are talking about smoking a turkey "low and slow." The reason people cook "low and slow" is because they are trying to melt out all the connective tissues in a large, tough cut of meat, and render all the excess fat at the same time. That process makes the meat super juicy and tender. The thing with poultry though is that it's already tender... there is no toughness to poulty when it's raw. Think about it like this : you ever put a meat probe into a raw piece of brisket? Super difficult to get the probe in, but doing that to raw chicken there is no issue at all with getting the probe in.
There are no connective fibers in a chicken or turkey which must be rendered out and there is certainly no abundance of fat either. So it's really just not necessary to cook a piece of poultry "low and slow" and you also run the risk of over-smoking the bird as it will absorb a ton of smoke at such low temperatures.
I have much better results cooking my poultry at 300-325 and I don't cook to time, but to temp in the breast. As long as you get the breast to 165 you can pull the bird, loosely cover it in foil, and it will continue to "cook over" ensuring the dark meat will hit 170. This also ensures that the skin gets crispy and super delicious.
Just throwing it out there because it's also much easier to only have to watch a piece of meat for a shorter duration. I did two turkeys on my offset, 10Lb and 12Lb, and it took just over 3 hours until they were finished. The skin was crispy and delicious, and the smokey flavor was there but not over-powering.
Edit: just about every single video or cookbook I've read says to smoke poultry at 300-325 as well.
Aaron Franklin :
Meathead from Amazingribs.com
http://amazingribs.com/recipes/chicken_turkey_duck/ultimate_smoked_turkey.html
So just tossing it out there, no right or wrong way to do it, just making sure people are aware of different techniques.
