Great research Bryan. For the past few years I have been doing research
on a growing group of print/caption flaws and I probably have more
unanswered questions now then I did before I started the research.
In my opinion the reason for a lot of the unanswered questions is
that the way they printed the sheets changed from series to series
and it even changed during the printing of a each series and each
back.
I don't think the printers fixed the Murr'ay I think the numbers are a
result of how they were printed based on my research of the group
of flaws.
One of the things I've found is if a flaw is found on a non piedmont
back so far it's always found at a larger % than the piedmonts. I think there
are a couple of possible reasons for this. They printed smaller sheets
of the non piedmonts and it depended on whether the plate with the flaw
was used for a particular back. The other possibility is that larger sheets
of fronts were printed and divided in half or thirds to print two or three
different backs and only one would have the position with the flaw.
I'll use the Davis AMEP as an example of why I think you have the
numbers you see on the Murr'ay's.
The Davis AMEP is on one of the plate scratch sheets that based on the
scratches I know is at least 12 same vertical subjects high So only one
out of twelve Davis cards printed from this sheet would have the flaw.
Sheet 1B Front.jpg
img392.jpg
These are the numbers I have on that flaw.
Davis.jpg
Since the Piedmont backs were printed first there was probably some
sheets printed before the flaw occurred. The SC649's % is similar
to the Piedmonts but the Sovereign150 and SC150/30 %'s are
double the Piedmonts. All of the other the flaws have similar numbers
and the best explanation I can come up with is the smaller sheets/
less plates on the non Piedmonts.