.45 Mars Long

Type

Pistol

Place of origin

United Kingdom

Production history

Designed

1899

Manufacturer

Kynoch

Specifications

Case type

Rimless, straight

Bullet diameter

11.40 mm (0.449 in)

Neck diameter

12.06 mm (0.475 in)

Shoulder diameter

12.07 mm (0.475 in)

Base diameter

12.65 mm (0.498 in)

Rim diameter

12.57 mm (0.495 in)

Rim thickness

1.07 mm (0.042 in)

Case length

27.76 mm (1.093 in)

Overall length

35.66 mm (1.404 in)

Ballistic performance

Bullet mass/type	Velocity	Energy
220 gr (14 g) FMJ	1,200 ft/s (370 m/s)	700 ft·lbf (950 J)

Source(s): Textbook of Automatic Pistols
MUNICION.ORG

The .45 Mars Long is an experimental centerfire pistol cartridge developed in the late 19th century. The similar .45 Mars Short used the same cupro-nickel-jacketed bullet in a case shortened to 0.66 inch. 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. The cartridge headspaces on this conical forward crimp. This elaborate bullet seating was necessary to withstand the violent feed mechanism of the Mars Automatic Pistol. The case has a thin rim and deep extractor groove in comparison to most rimless pistol cartridges. 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.

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