I have a theory about grainy craft whiskeys. I think it's all about heat. Heat makes whiskey mature faster. Big distillers build big rick houses. The high floors get hotter in the summer and the middle of each floor takes longer to cool off at night. Consequently, some barrels are subjected to accelerated aging. When it comes time to blend a batch, barrels from all over the warehouse are dumped together, but some of them are from the fast-aging spots. Small distillers build small rick houses and don't get this effect.