Development of PP loads for the .44-77.

[Don McDowell]

I would guess that charge of Swiss to be much closer to 1300.
74 gr of KIK 2f would kick a 480 gr bullet at 1225, and Cartridge would do about the same. I upped the charge of KIK to 77 just to be sure to have plenty of room over the velocity requirements to shoot the nationals at the Whittington. Back then they actually chronographed every rifle with loads randomly selected out of you ammunition, during weigh in. Going to OE erased velocity concerns, and fouling problems.
Keep in mind the velocity coming from that bottle neck will be a bit higher due to all that powder gas being forced down thru the funnel shaped case mouth.
If that brass was fired in a C Sharps chamber you will have to size the base of the case down quite a bit to get it to chamber.