I wonder if the name is akin to Reuß-Plauen(Gera), a location where Carl Seyfarth in the mid 1800 was peddling hunting haberdashery along with sporting weapons with high quality pattern welded tubes.
I've been chasing the Boys Barthelmes and there was a Valentin D. Barthelmes active in the 1st 1/4 of the 19th century. A Samuel(Johann?) Barthelmes, Gewehrfabrikant in Zella St. Blasii, in Sachsen Coburg-
Gotha along with a Gustav Adolph Barthelmes in the mid 19th century. In 1849(May 22nd) there were adverts for claims against the estate of Johann Samuel Barthelmes so he may have expired then? Kley & Barthelmes was a partnership in 1862. A year later a firm of Ritz & Barthelmes, Valtin Bernhard Ritz and Ernst Heinrich Emil Barthelmes, was founded but I'm not sure just what business they had. Also there was an I.S.(J.S.- Johann Samuel above?) Barthelmes mixed in there somewhere & he just might have been a tube maker as he was sourced by several including a F. Rubesch of Prag(1816-1896).
I've often wondered who the mechanic might have been that devised the pop-up sight on drillings when the solid projectile tube is selected. Don't know for sure and do not have the diagrams but the concern Emil Barthelmes obtained protection in 1896 for some pop-up sight variant for multi-barreled sporting weapons:
Visir für mehrläufige Gewehre, bei dem das willkürliche Aufstellen und Niederlegen der Visirllappe(??) durch die Spannung einer unter dem Visir liegenden Bogenfeder bewirkt wird - Firma Emil Barthelmes Zella St. Blasii for 13th November, 1896.
I don't know the Gebrauchsmuster/D.R.G.M. number but as one can read it was in late 1896. They also sought protection for their ideas under other Gebrauchsmuster/D.R.G.M.s like 200043 on April 25th, 1903.
Kind Regards,
Raimey
rse