I use the term High Brass for any heavy game load. Presently, I hunt with Super X 1 1/4 Oz shot at 1330 FPS, so these are pretty hot loads. We hunt in pretty tall timber in our area and haven't had as good of luck with bird loads. I will also use Remington of about the same load.
In my squirrelly past I found that heavy loads at higher velocities are not the best way to address high squirrels. In a shotgun, larger shot sizes at 1150 - 1165 fps IS the way, and usually gives tighter patterns at range. That failing, God made the .22 LR, which early on became my squirrel gun of choice. Squirrels can be taken at nose-bleed altitudes with that.
JMHO, YMMV
