So I've got some strange things happening. I had a big order coming up for beer mugs, so I did a shrinkage test in a kiln that was mostly empty. (Probably 20 pieces) it's the big oval skutt kiln so it can fit around 150 mugs. I did a slow cool at 100 degrees an hour down to 1900. So my pieces came out and they were slightly smaller (>1 oz) than what I wanted so I threw them 1/8" taller. Wet size 5 3/8" H x 4 1/4" W. Loaded the kiln with around 120 pieces and shortened the cool down to 100° an hour until 2000°. Witness cones tell me it was slightly cooler, I shortened the cool down because it seemed to cause the kiln to achieve slightly over cone 6. So I take out the mugs, and they shrunk more this firing. How is that possible? I used a throwing gauge to make sure they were uniform. They shrunk more in width this time and ended up the same height as the ones that were 1/8 shorter. Any input would be great, I'm newish to pottery and live far away from any large studio. Sorry it was so long I just tried to give all the info you would need. I'm wondering if because I pulled the clay slightly larger resulting in slightly thinner walls that it caused it to shrink more?