44-40 was loaded with 40 grs of black powder (hence the name)

[prison/con.net]

in order to get the sort of ballistic perforance that today, we get with 5 grs of Alliant Bullseye powder. which is to say, 200 grs at 900 fps in a pistol that's 9" long. So you see, blackpowder is just 1/8th as powerful as the fastest burning smokeless powder (that's available to reloaders). .22lr powder is faster yet, as is blank powder. If you can't get enough Bullseye under your superlightweight bulllets to make the cases expand at the web as much as a normal bullet weight "plus P" load, then the next step is to use .22lr powder, carefully working up the load, 1/2 gr at a time, watching the velocity on the chronograph and miking the fired cases at the web. If you go up a full grain without any velocity increase (to speak of, average of 3 shots). then back off the load by 1 grain, cause you're at the max-safe load, regardless of what velocity or case expansion you see..

 

[WinterBorn]

in order to get the sort of ballistic perforance that today, we get with 5 grs of Alliant Bullseye powder. which is to say, 200 grs at 900 fps in a pistol that's 9" long. So you see, blackpowder is just 1/8th as powerful as the fastest burning smokeless powder (that's available to reloaders). .22lr powder is faster yet, as is blank powder. If you can't get enough Bullseye under your superlightweight bulllets to make the cases expand at the web as much as a normal bullet weight "plus P" load, then the next step is to use .22lr powder, carefully working up the load, 1/2 gr at a time, watching the velocity on the chronograph and miking the fired cases at the web. If you go up a full grain without any velocity increase (to speak of, average of 3 shots). then back off the load by 1 grain, cause you're at the max-safe load, regardless of what velocity or case expansion you see..

Considering the fact that blackpowder burns slower, in order to maintain safe tolerances, you shouldn't fill the case with smokeless powder.