one thing to add, I have cooked many thousand pounds of brisket, injected / not injected ..packers or just flats...and the only time I had a dry flat was when I get into aging past 30 days,,I was doing 60 days and they came out tasty however they were on the dry side..so maybe something to think about and even if I left a thick fat cap...dry..soaking in any liquid the cells will not absorb, we think they do but they just will not coperate
I use what ever for a rub however I always put a layer of brown sugar or turbinado on. It does not matter if I am cookiing one brisket flat or 3 cases, they get some sugar..
Try to cook with out any injections, and you learn what might be the problem, then add the injection, as you have to learn how to cook the meat first. You should be able to cook a brisket without any wrap and it should be juicy, then the injections are a nice plus..a wrap...but remember wraps soften the bark...
as the Bludawg said probe like buuter...then rest ....then enjoy
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