I have a good set of calipers that I am using for the build of the Halisnki P-51 D. I know that .20 = .5 mm (If memory serves....). So when I put 2 pieces of this stock together they should equal .40 on the caliper which is 1 mm, no? I put 2 pieces together and I measure .45-.50..... Add a third piece and the error gets even bigger..... What gives? And this is without any glue. Just piled on one another and measured. The calipers are not digital. They have a dial on it which I have "zeroed out" before measuring. I'm stumped.