This work addresses the variation in wall loads in thin, smooth walled, flat floor metal silos caused by the variation in the mechanical properties of the grain bedding and friction forces acting on the grain-wall interface. Experimental effects shown and discussed are not fully covered by standard design codes. Background of some of these phenomena is still poorly understood, and as such a satisfactory theoretical description for the causes of these phenomena cannot be offered. As illustrated by experimental results, these effects can cause additional loads to occur on silo walls.