doublegunshop.com - home Forums General Discussion Double Rifles, Paradox Guns & Gauge Rifles @ doublegunshop.com An unusual 24ga W. Collath Double Rifle

Collath advertised double rifles in common and Express cartridges but also advertised that upon request would make one in any domestic (German) or foreign cartridge. Therefore, the rifle could be chambered for practically any cartridge, including those that would be nominally the same cartridge but would have differing chamber dimensions depending on whether brass or paper cases were to be used (this could also affect rim diameter/thickness). Diameter of a bullet to be used in a paper case cartridge could differ from the diameter of the diameter of a bullet intended for the same nominal cartridge but intended for use in a brass case. Since you have discovered an apparent discrepancy in chamber diameter vs bore diameter, this might be the cause. With the chamber cast (I'm guessing it is long enough to show bore and groove diameters) I'm sure you can sort this out, I can't.
Mike