You can add Lefever's found with LLH and SB&Co markings. It is not clear if SB&Co was importing the tubes and simply reselling or perhaps actually did something to them. There is a 3rd mark, a diamond that also appears. Until recently, I always thought that was a SB&Co mark.

Some Lefever guns have surfaced without the diamond, also a few with only the diamond. Also Lefever guns with damascus barrels and the SB&Co stamp have surfaced.
Go figure.

Here is a history of the SB&Co company.
http://www.sandersonsteel.com/200_years.htm

LLH info
http://www.littlegun.be/arme%20belge/art...aurent%20gb.htm

Pete

http://www.damascus-barrels.com/Movie.html