12mm Dumonthier?

I have what I believe is this round, its details are

case 14.4mm Rim 13.10mm Cal 11.8mm OL 26.49

No headstamp, brass primer, round nose lead bullet, the only info I could find was a drawing and some details in an old ECRA journal , I know Dumonthier made Walking stick/Canne guns in 9 and 12 mm but thats all, can anyone help with any other info, has anything else been published on this round ? thanks Randy

I’ve had a look at the ECRA data CD and the average measurements for 7 different rounds of 12mm Dumonthier are ;

Case Length: 14.50mm
Rim Dia: 13.27mm
Bullet Dia: 11.40mm
Overall length: 25.42mm
Case Mouth Dia: 11.63mm
Case Head Dia: 11.70mm
Rim Thickness: 1.50mm

The cases for the 12mm Dumonthier, 12mm CANNE, 12mm DEVISME and even the 12mm French Revolver are all very similar.

The 12mm Dumonthier calibre is only positively identified by having the typical “D” in the hs: “G.* D.12 m/m” or “GG D 12m/m” (Battery cup)

The 12mm Canne is known without hs but that normally has a Gaupillat ‘Battery Cup’ primer type.

The similar 11mm Devisme was IP and generally had a “GD” hs.

Typically the Canne/Dumonthier case is 1mm shorter than the similar 12mm French Revolver but case lengths for the Rev do get as low as 14mm.

I would think that yours is most likely a 12mm French Revolver as this is known with normal no hs (ie not Battery cup) but it could also be a 12mm Canne.

Sorry, not too much help !?!?

Don’t you just hate it when you have a cartridge sitting in no mans land, I have only just been able to getting around to try and solve this one, thanks for the replies, according to Erlmeier & Brandt and White & Munhall my round is much to short in the case to be a 12mm French at .565in, to big in the rim at .520in and at .465 the bullet is to big or are these differences acceptable ? Thanks Armourer for the Dumonthier info, can some one help with Devisme data. Randy

Randy, put two pictures : one side view and one of the base