Primer,
I just thought I'd give the 200gr Shockwaves a try, just out of curiosity. Two shots, two dead deer that only traveled 50 yards each. the one through the shoulder left NO blood trail, the one behind the shoulder left a blood trail 4 to 5 feet wide, no kidding.
The Black Mag'3 powder is like a breath of fresh air, no horrible smell, lots of power like 777, small amount of fouling that allows you to seat another sabot without swabbing. I probably only needed about 80 to 85 grains to do the job, but used 100 grains to make sure I had enough power with the light 200gr Shockwaves. The powder is most like the old Clean Shot (now American Pioneer Powder) but the granules are very fine. I bought my BM'3 up at Jay's Clare store.
So far I like the powder, but have only shot sabots and one PowerBelt with it. I will do some Heavy lead slinging with it when the weather warms up a bit. I also need to work up a load with it for my White 12ga Shotgun for turkeys.
ELMO,
I have not done any extensive testing with BM'3. It does produce some fouling right at the face of the breech plug on the barrel walls, but does not hinder you from loading another sabot without swabbing. You will need to use a wet (spit) patch when you do swab however, otherwise it will grab your patch when the jag bottoms out.
One more benefit is that I can just use regular BP grease because the plug comes out with only my fingers on the wrench. The cleanup is also the easiest cleanup of any of the BP subs, and I have tried them all.
I have only scratched the surface on load development with BM'3, as I have only had three range sessions and two successful hunts with it. Sorry I can't give you more than that.