Brisket getting tough after a long rest?

Not sure what happened. I sometimes hold mine in a cambro for up to 6 hours. And they are very good!

Be Safe

THE DAWG

i have always had trouble with flat only brisket. a cooked flat most likely doesn't have the mass to keep itself moist and tender, like a whole packer would. both during cooking and resting.
but, possibly, did you vent the brisket before resting in a cooler? if not it may have overcooked itself because it was too hot.
i have coolered whole packers as well for six hours and haven't had issues.
good luck and have fun with your 4th cook!

"Total time 6 hours"

I recently made this mistake with just a flat. Thinking that because the piece of meat was smaller (than the packers I usually cook), I didn't think it would take as long to cook.....I WAS WRONG! (My wife loves to see those three words).
What I learned was that regardless of the size of the brisket, because it is one of the toughest cuts on the beef with the most connective tissue, only time at temp will break those connective tissue down into the tender delicacy we all look for.

In my case I put mine back on the smoker for and additional 3 hrs +/- until it was done. I spritz my briskets with apple juice about every 1-1 1/2 hrs and keep a pan of water in the smoker for humidity.

My guests had all gone home by the time it was done thinking "that was like shoe leather". However, I had a great late night snack and learned a valuable lesson.

Lesson: A BRISKET IS ONLY DONE WHEN IT'S DONE. :blabla:

I have cooked Flats only before and haven't had an issue, was it a warmed cooler when you put the brisky in? Did the brisky go direct from the smoker to the cooler? I have held brisky's from 3-4 hours before in a warmed cooler, wrapped up tighter than a baby.

You didn't cook it long enough. A brisket will tighteten up a bit as it cools. Make sure you're checking in multiple spots for doneness and not just in the point or at the very end of the flat. I find that I'm taking my briskets anywhere from 205-210 before they really test as done. After a rest the texture is perfect.