I am using VV N350 with very good results in a number of 9mm guns. I use a 124 gr. Montana Gold HP with 5.5 grs, WW SP primer. It is quite accurate and, as you say, very clean burning. Haven't noticed muzzle flash so I guess it's not an issue. I also use 5.0 grs. with lead bullets of the same weight. You can go as high as 5.7 according to the Vihtavuouri website. I have seen other sites such as Handloader.com recommend as high as 6.1 but I don't like to exceed Vihtavuouri's data. It is a nice load to shoot, very accurate and easy on the brass and gun. The only downside to this powder that I can see is it's cost. I lucked out and got a couple of 4 pounders for a ridiculous price but otherwise I wouldn't have bought it.