NAME – 9x20mmR

NAME (COMMON) – .38 Smith & Wesson, .38/200 (Mk Iz)

TYPE – Rimmed centerfire

YEAR OF INTRODUCTION – 1877 (1932 in British Service)

COUNTRY OF ORIGIN – USA

CASE TYPE – Rimmed straight

CARTRIDGE LENGTH – 30 mm (1.18 in)

CASING LENGTH – 19.7 mm (0.775 in)

CASE HEAD DIAMETER – 9.83 mm (0.387 in)

CASE RIM DIAMETER – 11.18 mm (0.440 in)

BULLET TYPE – Round nosed lead

BULLET DIAMETER – 9.12 mm (0.359 in)

BULLET WEIGHT – 9.4g (145 grains)

POWDER WEIGHT – 0.19 g (3 grains)

CASING WEIGHT – 4.05 g (62.5 grains)

TOTAL ROUND WEIGHT – 13.54 g (209 grains)

MUZZLE VELOCITY – 227 m/s (745 fps)

NOMINAL BARREL LENGTH – 10.2 cm (4 in)

MUZZLE ENERGY – 242 j (179 ft/lb)

     The original cartridge that this round was based on was the 9x20mmR (Smith & Wesson .38) originally released in 1877 by Smith & Wesson for their line of small top-breal revolvers. As such, the cartridge was originally a black powder round but made the transition to smokeless powder in the late 1880s. When Great Britain was looking for a replacement round for their 11.43x19mmR (.455 Revolver (Webley) Mk II) revolver and line of ammunition, they looked for a smaller round that would take less training time to teach troops how to handle the recoil of the new weapon with accuracy, rather than the heavy recoiling Webley. A 13 gram (200 grain) round-nosed lead bullet was loaded into the Smith & Wesson casing to produce the .38/200 Mk I z round, now loaded with nitrocellulose powder rather than cordite. There was a question raised that the lead bullet of the Mk Iz may be a violation of the Hague Accords against deforming bullets. In 1937/37 a new jacketed bullet was developed, the Mk IIz round. In this round the bullet was fully jacketed with a weight of 11.53g (178 grains. To account for the new round having different ballistics and point of aim over the previous Mk Iz round, a new foresight was issued to change the point of aim of the Enfield Mk 2 revolver. As the exigencies of war required, the British military ended up issuing both the Mk I z and Mk IIz round as the war progressed.

ADDITIONAL LOADINGS

NAME                            TYPE                                     BULLET WEIGHT          CARTRIDGE WEIGHT             MUZZLE VELOCITY             MUZZLE ENERGY

.380 Revolver Mk I z    Round nosed lead             13 g (200 grains)         18.66 g (288 grains)               180 m/s (590 fps)               210 j (155 ft/lb)

.380 Revolver Mk II z   Full jacketed ball               11.53 g (178 grains)    17.2 g (266 grains)                192 m/s (630 fps)               239 j (176 ft/lb)