Nick, you're on the right track! A couple of suggestions:
- Try to keep the temperature down between 200-225 degrees. You can cook them longer this way, which is critical when smoking (and yes, 6 hours is the target time). A higher temperature will cook them faster, and you won't get the "smoke ring" if they cook too fast. (A "smoke ring" is when the rib meat turns pink...a sign that the smoke has actually cured the meat a little bit). At 250 degrees, your ribs will be on the edge of overcooking at about 4.5 hours.
- "Fall off the bone" is actually a sign that the ribs are over-cooked. You want the ribs to be at a point where if you tug at them, the meat is at the very beginning stages of separating from the bone, but not actually falling off.
- I recommend putting a small coating of the BBQ sauce on the ribs with about 1 hour left of cooking time.
I did a couple of racks yesterday: