I was once an avid homebrewer, and was consistently able to hit my OG without any problems. I used grain milled by BWS. I batch sparged in a cooler with a braid. It was never an issue.
Fast forward 3 years of brewing inactivity. I'm back into it and have done 4 batches with a very uniform 66% brewhouse efficiency. The first two brews were with grain milled by the HBS. The last two were brewed with grain milled by me in my Monster 2.0. I bought the mill hoping to improve efficiency. I'm missing my OG rather consistently by .005 each time (1.064, not 1.069 etc.).
I also have found that my cooler has an odd temperature problem. I preheat my cooler before starting. Then I mash in. After stirring well, I'm seeing anywhere from a 5 - 10* temperature flux between the left end of the cooler and the right end of the cooler...could that really be right? Looks like if stirred well then that should not be an issue, especially in a pre-heated tun.
As for sparging, I split it into two sparges. 185* water. Pour in, stir, let sit for 5 -10, vourlauf, drain. Again, I do this twice.
I'm not sure why I'm not getting better numbers. I hate missing my numbers. The beer tastes fine, but it's a mental thing. I'm not 66% at anything else.
Should I tighten up my mill? It's set at .39. All the kernels are busted. I'm not seeing a ton of flour, and a lot of flour sticks to the side of my bucket. Should I be sweeping that into the mash?
Would the temperature differential have something to do with it? Why is there such a severe difference I wonder?
Am I sparging improperly?
It's just a gigantic gaum at this point. I'm pretty pissed about it and need someone to give me a hug and tell me it will be ok.
Seriously, what am I overlooking? What would be your checklist?
All help is appreciated. I thank you in advance.