"Express 400-500" suggests a .40/10mm rifle cartridge, maybe on a necked down .500 cal. case, and I see "10" (mm?) on the rifle barrel. The Drilling was obviously made for the German market so a peek into the 1904 DWM catalog could produce some candidates; let's see:
Express Kal. 400: 10,35x60,90 mm - DWM case 76 (bottleneck)
Express Kal. 450/400: 10,40x82 mm - DWM case 76 B (bottleneck)
Express (unnamed): 10,25x68,90 mm - DWM case 214 (bottleneck)
(Lancaster): 10,35x65,40 mm - DWM case 164 (straight).
Cheers,
Jani
| 