avoid the lil gun for your cast stuff, especially if non gas checked.
its a known "hot" burning powder. as such i can verify that it will burn right through powder coating on the base at supersonic levels and you'll be spraying lead out of the end of your barrel. I had it happening even with some mild loads i was testing in my 300 blk a while back - i had to scrape lead off my magnetospeed blast sheild with a knife after only like 15 or 20 rounds. No more lil-gun and cast for me.
did you take the extra step and de-lube those bullets before you PC them?
one other thing to note - some of the HF powder coat paints have a lot of silica in them. the wrong powder with too much silica can be like runing sandpaper down your bore.
Most folks i know who are powder coating are using polyester 400* TGIC from powder by the pound like this
https://www.powderbuythepound.com/cherry-starburst.htmlsome of their per pound pricing seems a bit steep, but many of their powder coat powders you can get in 2oz packs for $5-$10.
you can pc HUNDREDS Of bullets with 2oz of this stuff, and dont even need to use a gun to coat with it - it can be applied simply by putting some bullets in a sealed tub (think tupperware or butter tub), scoop some powder in, and shake for a few mins. sift through some 1/4" wire screen, and bake.
feel free to take a look at this thread. there's some great discussion about PC and how to go about it really easily. probably more than you ever wanted to know about powder coating bullets.
http://www.300blktalk.com/forum/viewtop ... 85&t=86939i bake mine in an old toaster oven i picked up yard sale'ing for $5.