I've seen a fair number of fairly early 3" guns proofed at 1 1/2 oz. So, we might conclude that 1 1/2 oz was a reasonable maximum service load for such guns. I'd guess that the 1 1/4 oz may have been more of a pigeon ring load, similar to the 2 3/4" loadings.

XC, for shame that you would try to confuzz usun pour kolonilz with big wordz like kattridge. Shelz is so much easier to spell.