Loren, it is chambered for a 44-40 loaded with bird shot. This is known as a the 44 Shot or 44 XL. There was also a loading that used a round lead ball called the 44GG for 44 Game Getter. If you decide to load your own, let me know. Do not use the load data for the modern 44-40 as a starting point.

Harrington single shot with the chamber markings for 44 shot.


No shot cup over shot card used.

Paper shot cup



Wooden shot cup


Pete