Inconsistent terminology of calibres

Many cartridges use a combination of calibre and charge weight to define them. For example; .40-110 Winchester Express is .40" calibre with a 110grs. black powder charge. This convention holds good for many others such as the 40-50 Sharps; 38-90 Winchester express; 32-44 S & W target; 45-70 Government etc.

However, Logan shows a reversed format for rimfire cartridges such as the 56-46 Spencer (.46 cal.); 56-50 Spencer (.50 cal.); 56-52 Spencer (.52 cal.). Can anyone please explain this reversal of calibre and charge?


Neither number in the Spencer cartridge designations refer to powder charge. The original Spencer cartridge was the 56-56 which refers, I think, to the case dimensions which are .56" at the neck and .56" at the base. It is actually 55 caliber with a 45 grain powder charge. Later cartridges probably derived their names because they were “based” on the 56-56. However, none of them are truly .56" at the base. Bullet diameters are close but not exact.

But, that’s how I think they came to be called 56-52, 56-50, 56-46, etc. It’s hard to find two Spencer cartridges, of the same designation, by different manufacturers, that are the same in dimensions. Maybe someone else has a better grasp on it? I gave up a long time ago.


One comment that could be added about the Spencer family of cartridges is that while the .56 and .56/46 are specific to a single chamber, the .56/50 and .56/52 are interchangeable with each other. The original design of this pair was the .56/50, designed by the U.S. government; Christopher Spencer didn’t like the long case body and shortened (and necked) it. After these cartridges passed into the commercial realm things got stickier yet, as some manufacturers continued to make the .56/50 according to the original government design, while others didn’t. Winchester’s .56/50 and .56/52 are so alike only a micropaleontologist can tell them apart.

The British cartridge designations like the .577/450 and the .297/230 were, I believe, similarly derived. Jack