Are you wrapping once you remove it from the pit that will help to soften the bark. I have never used foil during a cook and just recently taken to using butcher paper with great results. I cook at 300 grate temp. I remove all hard fat from the exterior. S&P is the only rub I use on my briskets. I don't take temps i cook by feel.
This was a 15 lb choice packer cooked unwrapped and tented on the counter with foil at probe tender until the IT dropped to 150. cook time was 6.5 hrs 2 hr rest
slice from the flat