Oh yeah, thats my favorite! I use XTPs as well, but I love the Sierra. I LOL'd when I first heard them referred to as "flying ashtrays". Cuz thats pretty much it.
Lemme go check my data and come back with my recipe.
Okay im back.
6.5 grains of Unique, gets them going an average of 840FPS out of my FNP45.
Stout, but not super hot.
5 grains of Bullseye will net the same FPS, but I think the recoil is a tad more sharp.