Since going all grain I've been using Marris Otter in my English style and bigger beers. But every time I mash it (between 150 & 158) I get a lower OG. Recently I brewed 2 pale ales, and English and an American. I kept the grain bills exactly the same but replaced 40% of the base grain in the English with Marris Otter. I mashed them at the same temp but the OG of the English was 1.043 and the American was 1.05. Is this normal?