Look in Dale's book and you'll read when both the Narrow Ring and Wide Ring inlaids were made/used (circa).

You won't see that "B" in any of the series, either.

The chip in question has two different style letters... and the chip may e a lot more than just any run-of-the-mill custom made chip... and there may be a very good reason why the owner chose the "B" seen on the chip and not the one in the series.

JB