I have no information regarding the barrels of A&N CSL, but P. Webley & Son began using Siemens steel barrels about 1880 and reported excellent results.
Shooting, Thomas de Grey Walsingham, Ralph Payne-Gallwey, Gerald Lascelles, Archibald John Stuart-Wortley, Simon Fraser Lovat, Charles Lennox Kerr, 1886
http://books.google.com/books?id=MT9NF4BnAFIC ‘Siemens’ steel barrels are fairly good and very trustworthy for cheap weapons...
The 1891 Birmingham Proof House report listed several other domestic steel barrels
https://docs.google.com/document/d/1cvqRzkg0wEjhAAcFWr8gFi7aPFRsSIJ_hahfDxmrNAU/edit