8.5mm Mars
Type Pistol
Place of origin 22x20px United Kingdom
Production history
Designed 1899
Manufacturer Kynoch
Case type Rimless, bottleneck
Bullet diameter .34 in (Bad rounding hereScript error mm)
Ballistic performance
Bullet weight/type Velocity Energy
139 gr (Bad rounding hereScript error g) FMJ1,550 ft/s (Bad rounding hereScript error m/s)740 ft·lbf (Bad rounding hereScript error J)
Source(s): "Textbook of Automatic Pistols" [1]

The 8.5mm Mars is an experimental centerfire pistol cartridge developed in the late 19th century based on necking down the .45 Mars Long case. The bullet has two deep cannelures, and the case is crimped into both. The case mouth is chamfered on the outside to fit flush into the forward cannelure. This elaborate bullet seating was necessary to withstand the violent feed mechanism of the Mars Automatic Pistol. The cartridge headspaces on the shoulder adjacent to the neck. The case has a thin rim and deep extractor groove in comparison to most rimless pistol cartridges. There was a very similar 9mm Mars cartridge firing a 156 gr (Bad rounding hereScript error g;Bad rounding hereScript error oz) bullet at 1,400 ft/s (Bad rounding hereScript error m/s). The Mars cartridges were publicized as the most powerful handgun cartridges through the early 20th century; but less than 100 pistols were made and manufacture ceased in 1907.[1]

See also Edit


  1. 1.0 1.1 *Wilson, R. K. Textbook of Automatic Pistols, pp.236-237. Plantersville, SC: Small Arms Technical Publishing Company, 1943.

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