Well to bring this one back, I chronographed some balls over pyrodex rs out of an open top colt clone yesterday and was really surprised at the numbers. 35 grains of pyrodex rs will launch a .454 140 gn ball to about 980 FPS. I use pyrodex rs because I had a good bit of it given to me. Otherwise, if I have to buy it, it will be Old E powder. A 35 gn charge of Old E powder gives me 1100 FPS out of an 1858 NMA. Grafs black powder is the slowest of all I tried at 890-910 FPS. SD numbers for all of them are in the upper teens, but all my loads are very accurate. I was really surprised as pyrodex rifle powder giving the velocity it did, I would have guessed under 900fps.