Make sure you make double lung shots with those 40 cal sst's because they are explosive. No shoulder shots, etc.
Kyle Pittman of Pittman Bullets is an awesome guy. Meet him in person or talk with him on the phone and you will agree. Kyle lives about 45 minutes from me. When we started building 40 cal sml's with real magnum rifle twist rates and bore diameters (1:13.2 to 1:16 Rock Creek .408 Cheytac barrels), there weren't any good bullets out there. I went so far as to anneal, swage down some .411 Barnes bullets and then full form them. They shot pretty good though.
Kyle engineered the Accumax 225, 250, 275, and 300gr bullets, had dies made and had a test batch ran. I ran some loads with various powders in Quickload. He brought 12 of each weight bullets 225, 250, 275gr and I brought the never before fired loads and my rifle to the Norris rifle range. What transpired that day was nothing short of amazing. Here is one of the targets.
THIS LOAD IS NOT FOR USE IN A BREAK ACTION.
A 225gr Accumax was propelled 3383fps into a .210" group at 120 yards by an untuned never before fired load. I have other groups from that day that are nearly this good with other powders and bullet weights. We also tested the 225gr saboted in Kyle's Krieger barreled 45 sml that day and saw right then that it would stabilize from a sabot and shoot accurately.
I can run a load for the saboted 225gr Accumax in a 45 break action with DI ignition. You could also use the 250gr 45 cal Accumax sabotless. If you're shooting sub moa with the 40 cal Accumax I'd say you have your load. Also, if you're getting 2800fps out of the 225gr bullet, you need to hunt with the hard core version that Kyle sells.
This target is a 250gr Varget load from that same session. 250gr bullet at 3401fps at 1/2 moa untuned load.