Once the roast reaches an internal temperature of 125°F, remove it from the smoker and pour the butter drippings of beef stock into a bowl. Increase the smoker temperature to 400°F, and sear the roast until the internal temperature reaches 135°F for medium-rare. Bottom round roast should be smoked at 225º F (107º C) for around 2 hours until an internal temperature of 130º F (54º C) is reached.