I really like HS6 in 9mm but have found it likes high pressure.
Ab-So-Lutely. With HS-6, it's all about the pressure.
I use HS-6 a lot and have extensive experience with it. I like it. But . . . it has a lot of - shall we say - "personality." Basically, it runs dirty and sooty, with a lot of unburnt propellant flakes everywhere, when it's underloaded - and that's often. It will tell you what it likes by cleaning up as you move up the powder charge. When it's real happy, it'll run clean as can be. And that will be at the high end of the load data (usually).
I'm the kind of loader who isn't happy when my propellants aren't. I strive to run my propellants in their wheelhouse. And if that doesn't fit the application, then I change propellants.
Over the years, I've learned that HS-6 is not particularly versatile. Where it runs the best is in semi-auto cartridges (that don't have extra space like revolver cartridges), with heavy bullets. So you're half-right - 9mm Luger. But the other half - the 115g bullet part - you will find to be a little problematic. In the 9, HS-6 would much rather push 124's or even 147's. It'll drive 124's to defense level strata. But it actually runs best under 147's. They'll be short of max velocity, but they'll run really clean and consistent, and would make excellent range/recoil practice rounds. One of the most important things I've learned about HS-6 over the years is that it really likes pushing heavy bullets - regardless of caliber.
You can most likely build good ammo with 115's/HS-6. But I'll tell ya' right now, you're going to have to pump them up. Way up.
The good news is that HS-6 is very forgiving with a pressure curve that is almost always gradual, linear, and predictable. It is not a "spikey" powder. And that's why I recommend it for novice loaders. Probably the friendliest powder in its burn rate range.
Have fun with it. Oh, and grab some heavier bullets when you get a chance
