It's a long read but please endure and see if you can help me out.
Ok....so for Christmas I decided to try my first attempt ever at brisket. I got a 15 lb. packer and I was all ready for a super long cook based on the 1 to 1.5 hour per lb. guideline. I got it all trimmed and seasoned and on the Lang 60 at exactly 9PM on Christmas Eve - fat side up and the point facing away from the smokestack. My goal was to use all Texas post oak and keep the cooking temp 250-270. At 11:30PM my Maverick 733 (which I always test before cooks) was reading 160 IT in the flat. I thought to myself that this couldn't be right if the meat was only on the grill for less than 3 hours. Do I pulled the probe and put it in another point in the flat. The new probe point read 134 IT so I felt that was more realistic. Once the probe read 160 I was preparing to get ready to wrap it in butcher paper, but I decided to probe it in other areas first. My readings were all over the place in both the flat and the point. Some places in the flat were reading as high as over 170. and some places in the point were reading as low as 140. At this point I figure maybe I am hitting pockets of fat in some spots but I am still totally confused. So I found a spot in the flat that wasn't 160-165 yet and probed there until I reached 165. I then wrapped with butcher paper and put it back on the smoker, but I couldn't find my probe spot again! So I just picked a random spot on the flat to probe and I let it ride until the temp was 195 IT. Then I used my Thermapen to probe for tenderness. While really tender in certain points of the flat, I was still getting temp readings that were all over the place. So I made the decision to take the butcher paper off and let it smoke unit it read a constant 195 throughout the flat. It was exactly 10AM when I got constant readings in the flat, but the readings in the point were still pretty random, but I double wrapped it in foil and put it into a cooler surrounded by towels until 3:30PM. I pulled it out and it was still piping hot. I sliced the flat and it had an absolutely beautiful smoke ring. very easy to slice, but it was dry. Bone dry. SUPER DRY (failure). But it was flavorful. The point, however, was very tender and juicy (SUCCESS!). I have a feeling that a 15 lb. brisket should not have been done in a little over 12 hours. So my questions are....
What in the heck went wrong?
Why was I getting inconsistent temps in the flat during the cook? This was the second most perplexing part of the cook. Was it because I had the flat facing the wrong way? I did my best to not hit any fat while probing.
Why did it cook so fast? This was the most perplexing part of the cook.
I am assuming the flat was dry because I let it cook until I got consistent temp readings in the flat, correct? How do I keep the flat from drying out if my ITs are all over the place? Do I just pick one spot to probe and stick with it no matter what?
I have a USDA prime packer in my freezer, but I am now afraid that I am going to ruin it if I try to cook it. Any help or advice you can give me is greatly appreciated.