The page lists relative scarcity of some carbine variation. Shows 34 different variants and estimated quantity made.
It states:
The following information was provided by ******** and reflects estimates of good carbines produced after allowing for scrap.
If the number is correct for UN-Quality, that was a lot of scraped receivers. BTW, UN-Quality was down at 22nd on the list.
The War Baby series books may not be something the casual person with one or two carbines would invest in. But someone with a bigger collection who may want a more in-depth explanation with a lot of pictures will find them valuable. And it does have errors, like any other book.
Not trying to push WB3, as it is a little pricey at $150, but it is 952 pages of information with 1,328 illustrations. And continues the efforts and information from WB1 (512 pages $70) & WB2 (386 pages $60).