Under pressure with Precision powder

So I tried out the Precision powder because Varget was hard to find a couple months ago. I’m shooting a 308 with a 165 Sierra GameKing as a hunting load. I loaded up a ladder test starting at 41.1 and stopped at 44.1 grains. My Varget load with this brass/bullet/primer/rifle combo is 43.8 grains. However, almost all the cases were covered in soot after firing and so was my bolt and chamber. I swapped powders and the problem went away so I know it’s not my brass prep. Everything I’ve read online says that a case covered in soot means under pressure. Everything that is “advertised” says Varget and Precision are almost a substitute. I’m almost to max published charge. Should I keep bumping it up to see if the problem clears? If so then that would mean the Precision isn’t as close to Varget as they say.