I have a 3in SP101 and I use mostly 158gr Berry's plated over 4.6gr of Unique in a 38 spl case for plinking. I do load 15.3gr of AA9 with a 125gr XTP in 357 for fun. that is Minimum in the Lee's book with 17gr max listed. I get 1550 fps with my 3in and the 15.3gr 357 load. You need to use load data for the XTP because it creates higher pressure than standard jacketed bullets. Lee also lists H110 for the 357 in 125gr as 21gr min ad 22gr max. I would assume Hornady has data for the XTP also. The Lee book also lists loads for plated bullets but if you cannot find the data most people say use mid range lead bullet data.
The 101 is a lot harder to shoot accurately than my Blackhawk or N frame Smith but it can be quite accurate with correct grip and trigger pull.
As always be safe and verify this data. I would suggest the Lee book even though his loads run a little hotter than some other manuals because it includes XTP and plated bullet loads.