Very interesting information on your beautiful gun! I just thought I would add another example to your discussion. I own a H. Leue marked double rifle. It is marked H. Leue, Hofbuchsenmacher, Berlin. It also has the trademark of a lion in repose with Leue on the body. It also bears a crown over "U" and a Prussian eagle. The 23 5/8" barrel is marked 67/49 guage(.410 inch). The barrel is also marked with a crown over "N", and 4g GBP over St.m.g., and a crown over "N". This rifle also came with another barrel set fitted for it and made by O. Geyger and Co.,Berlin. This set of barrels is in 8.9mm. A very interesting rifle, which according to family members was owned by a family member living in Kenya in the early part of the 1900's. It was definitely a field gun, showing much even wear and use. I have some pictures if anyone is interested.
