I find Unique powder to be the cleanest in my 9mm shooting cast bullets. I tried Tite Group in it first, it worked well but I get better accuracy with unique and unique seems to be a little cleaner. I usually clean after 500 to 750 rnds wether it needs it or not.
I REALLY like Tite Group in my .45's. Again I am loading mainly cast bullets.... I am also very lazy cleaning them as well, usually after 500 to 750 rnds, or longer.
I tried a little test last winter. I wnated to see how long I could go without cleaning my pistols before they stopped working...... 1400 rnds in my 1911 Norc (I just couldn't do that to my Colt or STI) and 1750 in my M&P 9mm.... In my M&P it didn't actually stop working.... it just got so dirty I couldn't look at it anymore......
I short I have to say Unique and Tite Group are 'cleaner' burning powders..... Or my guns have a lot of clearance!
Cheers!
I've been using Unique in my 9mm and find the cases come out sooty as well. I just figured it makes it easier to tell which cases are mine on the floor of the shooting bay!!