[fred cook]

a .58 Carbine inside primed centerfire round circa 1867-8. It replaced the .58 rimfire round originally used in the Springfield rifles converted to breechloaders. The inside primed cases were of the balloon head style but having the primer assembly in the base made them less likely to burst at the rim. These rounds were only used/made for 3-4 years until the outside primed center fire ammunition was developed. Of course, the .58 caliber was used to allow the original barrels in the Springfield muzzle loaders to be retained thus lessening the cost to rebuild them into breechloaders.