I'm sure there is a slightly different story for each road, but the "window of utility" for the B&M car is rather narrow.  The paint scheme is 1946+, but the B&M's 500 cars were down to 24 by 1950, and just 3 by 1955. The other choices would have been the 1927+ scheme with the rectangular herald, or the as-built scheme.  Each of these would have persisted for about a decade,  but at least the full complement of 500 cars was in interchange.

The USRA cars were never more than ca. 15% of the B&M's box-car fleet, and were  likely even less  significant on many of the other roads. This release continues the tradition of making it all  too easy for modelers to over-represent the USRA cars generally.  Setting aside the Ertl option,  the USRA DS cars are already available from Accurail, Westerfield, and F&C.  Not exactly a gaping hole in HO scale.

Dave Parker
Riverside, CA