I doubt you'll get the top speed out of AA#9. It just isn't that energetic compared to Longshot, Power Pistol, Blue Dot, or 800x. You may get better accuracy though, and the push will be a bit gentler. As well, if #9 works, 2400 will also work.
Bad advice Huntnshoot.
Those comments about #9 are not at all accurate. It is pretty much the perfect burn rate and density for maximum velocity in heavy 10mm loads, and will meet or exceed the velocity you can get with any of the other powders mentioned. It's not at all like 2400, which can not generate good velocity in the 10mm because it's too bulky, you just can't get enough in the case.
OP, the Blue Dot you already have will give you pretty good velocity too. I'm not going to offer my load data, since the 220 gr bullets I've worked with are different than Rimrock's and that can have a big effect on pressure. However, I can tell you the biggest differences you'll see between #9 and Blue Dot are flash (lots for Blue Dot, very little for #9) and metering (#9 meters great, Blue Dot is less consistent).
