at 25 yards seated using open iron sights:
7.8gr Univ Clays /Black River 265gr SWC--1050fps---3/4" 5 shot group
8.3gr W-231 /Black river 265gr SWC---1114 fps----7/8" 5 shot group
8.5gr Unique /Black River 265gr SWC---1126fps----7/8" 5 shot group
15.4gr 2400 /Black River 265gr SWC ---1065fps----1.25" 5 shot group
So far this is the best I could get keeping power mild and accurate. I tried .453" Mt Baldy bullets but this gun likes the .452" black River 265gr SWC.

.

Thanks for the data. My AEs like the Univ. Clays powder very will and I shoot a lot of 2400 in them. Your accuracy and velocity is comparable to what I get with my 45s. Enjoy your gun, they are great fun.