6.5×58mm Vergueiro

The 6.5×58mm Vergueiro is a centerfire rimless cartridge designed in 1904 specifically for the Mauser-Vergueiro, chosen as service rifle of the Portuguese Army. It was adopted to replace the rimmed 8×60mmR Guedes and 8×56mmR Kropatschek Corto cartridges originally filled with blackpowder, which had been used with Kropatschek rifles procured in the mid-1880s. Smokeless powder allowed for a higher velocity round and further calibre reduction to 6.5 mm, a step already taken by other European countries, e.g. Sweden (6.5×55mm Swedish) and Italy (6.5×52mm Carcano).

6.5×58mm Vergueiro
Type	Rifle
Place of origin	Portugal
Service history
In service	1904-1939
Used by	Portugal Union of South Africa
Wars	World War I
Production history
Designer	José Alberto Vergueiro
Designed	1904
Specifications
Case type	Rimless, bottleneck
Bullet diameter	6.65 mm (0.262 in)
Neck diameter	7.56 mm (0.298 in)
Shoulder diameter	10.94 mm (0.431 in)
Base diameter	11.88 mm (0.468 in)
Rim diameter	11.78 mm (0.464 in)
Rim thickness	1.32 mm (0.052 in)
Case length	57.85 mm (2.278 in)
Overall length	81.50 mm (3.209 in)
Ballistic performance
Bullet mass/type Velocity Energy 155 gr (10 g) FMJ 2,347 ft/s (715 m/s) 2,000 ft⋅lbf (2,700 J)
Source(s): Rifles and Machine Guns[1] MUNICIOC.org [2]

It remained the service rifle cartridge until the Karabiner 98k replaced the Mauser-Vergueiro pattern in 1939.[1] The round was also used for sporting purposes, manufacturers like DWM and Kynoch offered it until the 1960s.

In military use the common projectile weighs 155 grains and travels at up to 2,400 feet (730 meters) per second. A lot of the Mauser-Vergueiro rifles were later rechambered to accept the standard 7.92×57mm cartridge of the newer Mauser 98k pattern.[2]