11.5X57Rmm / .43 Spanish Reformado

11.5x57Rmm / .43 Spanish Reformado

The 11.5x57Rmm, more commonly known as the .43 Spanish Reformado, was developed in the late 19th century as an updated version of the original .43 Spanish cartridge. The Reformado variant was adopted by Spain during a period of military modernization, intending to improve on the performance of the earlier bottlenecked .43 Spanish (11.15x58Rmm) round. Unlike its predecessor, the Reformado cartridge features a straight-walled case and a larger diameter bullet, optimized for use in re-bored and updated Spanish Rolling Block rifles.

The Reformado cartridge was part of an attempt to standardize and simplify ammunition logistics for Spain’s armed forces while improving stopping power. The bullet diameter was increased to around .454" to .456", and black powder remained the propellant of choice, typical of the time period. Military loads commonly featured bullets in the 390–405 grain range, propelled by 75–80 grains of black powder, delivering muzzle velocities between 1,300–1,400 feet per second.

This straight-wall case design not only allowed for improved feeding and extraction in the aging Rolling Block rifles but also simplified reloading for Spanish arsenals. However, the Reformado remained relatively obscure outside of Spain and its colonies. As the world moved quickly toward smokeless powder and smaller-caliber cartridges by the end of the 19th century, the Reformado was gradually phased out in favor of more modern ammunition, such as the 7x57mm Mauser, which would become the new standard for Spain by the 1890s.

From a collector and handloader perspective, the .43 Spanish Reformado is a fascinating example of an interim cartridge — a bridge between the large-bore black powder military rounds of the 1870s and the small-bore smokeless powder rounds of the early 20th century. Ammunition for it is now considered obsolete and is not commercially manufactured in volume. However, reloading is still possible using reformed brass from .348 Winchester or custom-turned cases. Reloaders must pay close attention to bore diameter, as surviving rifles often vary considerably due to hand-fitting and wear. Soft lead bullets sized appropriately to the bore and black powder or mild smokeless loads are recommended to preserve these historic firearms.

Surviving examples of rifles chambered in the Reformado are usually Spanish-made Remington Rolling Blocks, sometimes modified or re-bored from earlier .43 Spanish configurations. These rifles and their ammunition offer a unique glimpse into a transitional period in military small arms history — an era where black powder was still dominant, yet rapid innovation was changing the battlefield forever.

Source: Spanish military archives and multiple historical black powder cartridge references; designed for updated Remington Rolling Block rifles post-1870s.