Hmm…it does sound like you did everything right. Why do you think it was overcooked? Was it a little dry?
Brisket can be tricky to get to the right temp to render the collagen but not dry it out. It’s not nearly as forgiving as pulled pork.
A couple thoughts for next time-- 300 may have been a little too high an oven setting. The guy in the oven BBQ video I posted upthread went 225 for 15 hours. When I cook a brisket in my smoker I go about 275 with good results, but it’s difficult to get it any lower in my smoker. If you use an oven and have 15 hours to kill, may as well take advantage of the even keel heat. At about the 4:25 mark he does the ‘cut and squeeze’ and it looks plenty juicy.
I’ve also seen videos where, at the wrapping stage, they coat the brisket in beef tallow and wrap it in butcher paper instead of foil. I’ve even seen BBQ videos where they inject melted beef tallow into the brisket. That’s probably going a little too far-- top notch brisket joints get awesome results and it’s not like they’re injecting beef tallow into every brisket day after day.
