Info about this round, please


I am looking for further info about this round, I know It can be scarce.

10mm Nagant Revolver / 10 mm Nagant / 10x20 R Nagant

Thanks for your help.

Ado - all I have on this revolver is what is in the Erlmeier-Brandt book “Manual of Pistol and Revolver Cartridges,” Volume I. It describes the round as "Cartridge for a revolver of unknown design. According to statements made in recent publications, it is thought to have been intended for use in a Belgian-made Nagant-System revolver, but this had not been confirmed at the time of publication of this volume in 1967.

The round pictured has a shouldered case, but the position of the shoulder is relatively unusual in that closer to the rim (head) of the case than it is to the mouth. Dimensions are:

Bullet: 9.95 - 10.05mm
Case Neck: 10.32 - 10.36mm
Case Head: 11.00 - 11.02mm
Case Rim: 12.25 - 12.28mm
Case Length: 20.05mm
OAL of Cartridge: 29.90mm

The specimen pictured has a brass case and lead bullet. I have to assume it is a normal Berdan Primer system, as under primer the only note is “Berdan.” It is indicated that it is a black powder cartridge. No headstamp is shown or described and there evidently are no other names *synonyms") for this cartridge.

I hope this is of some help to you. Oh yes, it doesn’t place any date on the cartridge - not even a decade. I assume that being a black-powder round, it is from the latter part of the 19th Century.