I often see sooty case necks on my .22 Hornet brass with 'Lil Gun. I don't worry about it, nor do I worry about the velocity variations. It just shoots great, and that's all I'm concerned about.
Regards, George.

I too see more than expected "soot" on the case necks of my Fireball brass when using LilGun, and chalked it up to whatever coatings/deterrents are added to the powder granules. I use 16.5gr behind mollied 40Vmax or Sierra hp's, with velocity in the mid-3500fps range.
AA1680 will also provide top speed with the 40gr pills, as another option, since every rifle has it's own "favorite".

Had some fun with 30gr Bergers using 17.5gr LiLGun...avg velocity was 4030fps...from a Fireball, and they grouped around 0.7", only dropping 1.5" at 200yds. Have yet to try them on a crow (no PD's in Central TX).

Over 4000 fps in a fireball ? Now you got me thinking. Just when I decided not to mess with success in mine......I'm startin that load development thing all over again.