The tube steel is that of Heinrich Ehrhardt and there was a strong sourcing relationship between Imman. Meffert and Heinrich Ehrhardt, so strong that my guess would be that they were related by marriage.

Heinrich August Theodor Ehrhardt was born in 1840 to simple beginnings, and retired & expired(1928), in Zella Saint Blasii where in 1866 he founded his first firm which faltered. It was then that he moved to Düsseldorf where he founded the Rhinish Metal Works Rheinmetall and made many wares including corkscrews. He real 1st success was a new technique of bullet making where he fabricated 8x57I steel jacked bullets for the M88. He then went on to bigger and better bullets, and tubes, for artillery pieces in the last decade of the 19th Century. It was then that he developed his tube making process and it has been pointed out to me that the square bolt/rod in the round hole, which can be seen in the diagram between the signatures in the signature block, became his trademark. Note the trademark on sheet 5 in the diagram: http://www.google.com/patents?id=S2x2AAA...rdt&f=false

The firearms merchant was O.(Otto??) Bennewitz and he placed an order with Imman. Meffert and had his name roll stamped on the top rib. Any chance the "EA" is "FA"? True the 1912 rules, not actual law, were the beginnings of addressing the lack of emphasis on the up and coming semi-smokeless powders. Some that were made before the rules, or during the transitional period, could also have experienced "Nitro" proof to be in line with the times.

True the ad hoc reinforcement addition isn't very easy on the eyes but there still seems to be some original musselshell reinforcement on the side frame, as you note, similar to that seen on F.W. Keler's examples.

9mm just seems to large for a pre-rifling diameter. Maybe Ford is reading from a late hour on riverview time and has an opinion. But I would 1st guess the diameter was 8,9mm and I can't say for certain if the diameter was 9mm that the stamp would be 9,0mm. No, they would not have stamped another diameter unless there was a reproof effort. Imman. Meffert didn't allow much engraving effort on their examples and their business model was to churn out as many quality pieces as possible. It may have been empirical data that led them to note that 3 quality pieces cold be produced to 1 upper rung example.

Have you attempted to chamber a 9.3X72R D cartridge?

Kind Regards,

Raimey
rse