A flat only. Costco. I know, I know. Once I get the recipe reasonably down I will search out the best packer in the area
Re thermometer, no it was not. I'll check that out. right away. The prep was simply trimming reasonable amount of fat leaving
a 1/4" and smoking fat side down.
I believe internal was 165.
And thanks for your interest.
Once all comments are in I'll give another try next week
I've gotten some good meat from costco before, i highly doubt that's the issue.
Your thermometer is your best friend in this endeavor, factory therms are notoriously bad. Check the one you have with boiling water and with ice water.
Your internal temp was way too low. You needed an additional 30-45 degrees. A brisket isn't like other cuts of beef, it needs to cook a LONG time and needs to get past 195° before it really begins to break down into something that resembles tender. Also, the fat and connective tissue didn't have a chance to break down at that low of a temp.
Try it again just like before but try the following
Rub as usual
Smoke at 225
When it gets to ~165 IT, wrap in foil
Allow to continue cooking at 225 until the IT reaches at least 195, 200 is better for this go around.
After the IT is reached, place the still wrapped brisket into a cooler with some towels on bottom and then cover with towels and let it rest for at least 30 minutes.
Then, open it up, slice and enjoy...