No, dont know of any books.

Agree ANY DF D/R is worth owning.

Someone here can correct me if i am wrong BUT I think DF
made best grade BOXLOCKS but of such high quality.
A bit like Trigger plate actions and WR Droplocks are considered high grade guns even though "technically" boxlocks".

Here are a few more
- Scalloped actions in Westley Richards are generally a higher grade of gun. Hence my comment. Where a gun is scalloped, it makes it harder to put checkered panels on the side as they don't have a straight line of the action to work with - and IMHO, you don't need both !!!
- Staling safety - some low grade guns have them. I have a low grade WR boxlock that has it !!! Why - because it was built as a hunting rifle !!!

Remember, in the days these guns were made, a lot were made to order so a gunmaker made what the customer wanted - chosen by funds available or features wanted.
That is why we have a saying, in the English gun trade
everything is possible !!!

Re the gun here in Aus, I just remembered, it went
to a guy in NZ !!! (I forgot it was a while ago - sorry !!!).