Long Cook Temperature Question?

[miami smokes]

Hey all. I'm going to long cook a brisket in an offset smoker and have a newbie question. I've heard rule of thumb is to cook 1-1.5 hours per pound of brisket at 250 degrees. 

Is 250 degrees supposed to be the ambient temperature in the smoker or the internal temperature of the beef?

I'm going to mod my smoker to put in a 3in temperature gauge but am unsure if the gauge should be sticking into the brisket or just above it outside of the meat. 

 

[dirtsailor2003]

250 is the temperature of the smoke chamber. Depending on whether you are going to pull it or smoke it the IT temp can vary. For sliced I take it to 185-195 for pulled 200-205. I start testing it at 185 with a tooth pick. If it slides in easy it's ready. Don't be surprised if your brisket takes 2-2.5 hours per pound. Good luck and post lots of pictures!