USC Co Farrington primed .50-70 variations

Here are three variations of US Cartridge Co .50-70 Farrington primed cartridges. The center one has the small blister on the primer, while the other two have concave primers. The one on the left has an uncharacteristically flat head. These Farrington primed cartridges typically have rounded heads like the other two.

Guy: How do you know these are USCCO? is the farrington primer unique to the 50-70 for USCCO? aVic

Farrington primers were used only by USC Co for all of their centerfire cartridges, beginning in the early 1870s. While they used this primer for many years, the early style dished cup was soon replaced by a more conventional looking rounded cup, making the primer indistinguishable from other types.


Somewhere in my many cigar boxes I have a 50-70 (maybe it’s a 45-70) with the primer shown in your second photo. I always assumed it was either a reload or a faulty priming punch but it looks like I’m wrong again.

Do you have anything that indicates why the dimple???


I have never heard of an explanation for the blister, but it may have something to do with the internal disk that is held between the inner and outer cups. As my photo shows, the blister is not present on all of the concave primers, and is not always centered as the one in the photo is, so perhaps its just an occasional manufacturing anomaly, caused possibly by uneven distribution of the priming compound which pushes up a spot on the concave outer cup when the primer is assembled. The Farrington patent (#133,929) describes the concave outer cup, but does not mention the blister.