I'm casting 200 grain bullets for the 44-40, and have loaded 2400 in it with unburned powder left in the case and Unique without unburned powder.  These were light loads, too. 
Is this common with 2400?  I never had that problem in my 44 Mag, but then I was using Mag primers in that.
These were just the powders I had on hand.  Do you have any favorite loads?  I'm using the Lee bullet and Lee liquid alox lube.  
OK, I know about 40 grs FFG!  Just haven't done it yet.  
I'm shooting a Uberti Cattleman with a 4 3/4" barrel and bird's head grips.  It's beautiful!