No.1 Mk. III Stock Disk ID

[AP96]

I was able to acquire a nice 1918 SSA No.1 Mk. III today, but I’m having trouble finding any information on the markings found on the stock disk. Wondering if anyone can shed some light on the meaning behind these? I’d suspect they are for a particular regiment of some sort. Thanks in advance.

 

[7ECA]

Oddly enough there doesn't appear to be much out there in the way of listings of stock disc markings, at least easily available on the web.

There appears to be a book that covers the various markings, can't seem to find any .pdf's of it though.

"The Identification of Buttstock Marking Discs in British Service' by Peter Laidler.

https://www.ds-militarybooks.com/peter-laidler-burrstock-identification?search=stock