Does anyone have any of the books on them? What is the 2 or 3 vol. series that is fairly recent? I keep seeing them for around $50 each. Is that price in line with what you're seeing?

The book series I think you're referring to is "British Single Shot Rifles" by Wal Winfer. This comes in 4 separate volumes, each with a particular focus:
Vol 1 - Alexander Henry
Vol 2 - Gibbs Farquarson
Vol 3 - Jeffery & the Trade Farquarsons
Vol 4 - Westley Richards

These books are of recent publication (1997, 1997, 1998, 2000). They are of very high quality with lots of good photos and well researched information. The US$50 price seems about right.

Another book on the same topic is "British Falling Block Breechloading rifles" by Jonathan Kirton. I've havn't got around to purchasing this yet but I'm told is also very good.

Regards
RJW