Possibly a K in a jagged circle. It is some 9.3mm variant or a cartridge based on the 360 BPE. More than likely 65mm shotshell chambers. It must be some variant on Modell 6292 if it has a rear ocular. Seeing that it does not have the noses on the sides of the tubeset labeled as Burgsmüller's Sicherheits Verschluß or safety lockup with sideframe reinforcement, which was apparently covered under some D.R.G.M. Nr.( gebrauchsmuster ), it is not the Modell 6298. The Modell 6292 would have been advertised as "Extra Solide Hahn-Drillinge". Pin configuration is a little different.
Kind Regards,
Raimey
rse
