I've used International for handicaps, not singles. The above 1 oz load is lighter than I used--my load was 19.6 gr (31 bushing in my mec) with rem hulls, cheddite or wolf primer, and green duster wads. Fast and efficient out of a full choke XT.
Great for high velocity 1oz. loads. You can load this powder down too but the low pressures will give you an incomplete burn and leave raw powder in your barrel/s. Here's a good low velocity/recoil recipe. I loaded 1oz loads with 18.5gr, AA or STS/Nitro hull, claybuster WAA12SL (pink) wad, WIN 209A primer and was very pleased. For 1 1/8 try 17.5gr and a WAA12 (white) wad.