Until covered choppers became the norm for grain movement, many railroads used (Class A) 40-foot boxcars for grain. Cardboard "grain doors" were provided to shippers to be nailed inside the the steel car doors, thus turning the interior of the car into a makeshift "bin"..Since they carried food, cars in grain service had to be stenciled "For Grain Loading Only". A lot of grain shipments originated on rural branch lines that could not handle 286,000 pound covered hoppers. That kept the grain boxcars around despite their inefficiency.
The Buffalo Creek RR had quite a fleet of 40-footers in grain service. The BCK served mills and elevators in Buffalo and, in addition to "Grain Loading Only stencils cars featured a large flour bag herald.