There are other powders out there that would be much better suited to reduced loads. If all you are looking for is 1100fps then let me suggest another powder,SR4756. You will not be able to use current data for it though, as it is so anemic. A load between current maximum and older data minimum would be just fine for what you want.
There will be no unburnt powder or nasty residue such as you will encounter by downloading 2400. W231/HP-38, AA#5, Unique and other powders in that same burn rate will be much better suited to what you are trying to accomplish.
The "dirt" left behind is not the main problem with downloading powders. It is a factor but not the "main" one that I see. I am a numbers guy. Sometimes they correlate to accuracy, sometimes they don't. Being a stickler for the numbers, I hate to see erratic numbers pop up on my chronograph. When a powder is loaded light for it's burn rate, almost without fail, the numbers go to pot fast. To me that means that I am not putting it in a place where it can "win". I use a different powder at that point.
Case in point: I had 8lb of a MILSURP powder that loaded like AA#9 to H110. I wanted to find some loads that I could use in every caliber I loaded to take advantage of the $8lb powder. Well, what I got was huge ES and SD numbers. I quit and went back to the powders suggested for the loads.
FWIW
