I have just regulated a load for my Fabarm Aspen 9.3x74R double. The load is 64 grains of ADI 2209 with a 286 grain Woodleigh Round Nose. This load regulates at 100yrds and averages 2" or better with a scope. Close to 2300 fps. One way I found to keep track of which barrel hits where is I set up two targets and shot bottom barrel on one and top barrel on the other. Avoids confusion.

Good luck