Hello everyone!

After a bunch of research on my newly acquired Masquelier double rifle, I'm coming up a little bit clueless as to what the gun is chambered in. Hopefully someone here can help me out. I have included a list of measurements below, and a couple shots of the proof markings.

The previous owner was using 9.3x74R brass cut and formed to the chamber to load for the rifle, but I'm not entirely sure that was the correct case. He used 35 cal rifle bullets, which seems to go along with the "8.7" marking on the barrel. 9x70R (DWM 474B) & 9.2x70R (DWM 474E) seemed like possible contenders, but the case length is a little off.

OAL: 2.670"
Neck Dia: .387"
Neck Length: .400"
Groove Dia: .362"
Shoulder Dia: .427"
Rim Dia: .560"

Larger cartridge for reference is a 9.3x74R. The fired/formed case appears that it might be a little short for the chamber at 2.580"

Maybe the rifle was rechambered from it's original cartridge. I'm stumped.

I look forward to hearing what our resident experts have to say.

Thank you

-Brandon