12 mm Lefaucheux
Type	Revolver
Service history
In service	1858–1892
Used by	French Navy and French Army
Production history
Designed	1858
Specifications
Case type	Rimmed, straight
Bullet diameter	11.3 mm (0.44 in)
Neck diameter	11.8 mm (0.46 in)
Base diameter	11.9 mm (0.47 in)
Rim diameter	12.6 mm (0.50 in)
Rim thickness	0.94 mm
Case length	19.9 mm (0.78 in)
Overall length	30.8 mm (1.21 in)

The 12mm Lefaucheux is a metallic center-fire cartridge. It was originally created as a rimless pinfire cartridge using black powder employed by the French navy on the Lefaucheux M1858 revolver. Later it was adapted to a center-fire cartridge by the French Army in 1873 for use on the MAS 1873 revolver.

Overview

Originally, the 12 mm, was a classic Lefaucheux cartridge, with a side pin from its introduction in 1858 until 1873, when it was adapted and became a rimmed center-fire cartridge for use in the MAS revolver 1873-1874 then used by the French Army.^[1]

Features

These are the characteristics of the '12 mm Lefaucheux' cartridge:^[1][2][3][4]

• Brass case
• Caliber: 12mm
• Ammo: 12 X 17
• Bullet diameter: 11.30 - 11.40 mm (.444" - .448")
• Neck diameter: 11.80 - 11.85 mm (.464" - .466)
• Base diameter: 11.90 - 11.92 mm (.468" - .469")
• Rim diameter: 12.64 - 12.66 mm (.497" - .498")
• Rim thickness: 0.9 - 1.0 mm (.035" - .039")
• Case length: 19.90 - 20.00 mm (.783" - .787")
• Overall length: 30.77 - 30.80 mm (1.211" - 1.212")
• Primer: patented GAUPILLAT
• Total weight: 18.34 grams
• Bullet weight (lead): 12.80 grams
• Cartridge weight: 4.74 grams
• Black powder charge: 0.80 g

These are the most frequently encountered ("headstamp") tags:^[3]

• 1 / E / 82 / G. E
• 4 / F / 82 / G.E
• 1 / G / 82 / G. E
• 4 / G / 82 / G.E
• 4 / M / 82 / G. E
• 4 / K / 82 / G. E

In these markings, the initials "G. E" referring to the manufacturer "Ernest Gaupillat", and the other letter and digits referring to the batch (probably place and date).^[3]

Dimensions