A few comments:
"Book max" for any member of SAAMI, if they follow the voluntary standards, is 44,000 PSI for the .22 Hornet--which means electronic measurement. Even though the Hornet case is relatively thin, exceeding this somewhat doesn't make much difference in brass life, because it's REALLY low for modern centerfire rifle rounds.
The basic pressure was established back when many .22 Hornet rifles essentially used rimfire actions. Using a little more powder in a stronger action ain't going to make much difference--especially if you use a primer designed to take a little more pressure, rather than the small-rifle primers designed for sub-50,000 PSI rounds.
That said, I have yet to see any advantage in using heavier bullets in the Hornet for varmints, especially burrowing rodents. Lighter, higher-BC bullets--especially plastic-tipped--perform far better beyond 100 yards, with flatter trajectories, less wind-drift and more consistent expansion. Accuracy is also better, for all the same reasons--which is why small groups at 100 yards in relatively calm conditions aren't very indicative of longer-range performance in even moderate winds. Which is why even in Hornets with typical too-short magazines for 40-grain plastic-tips, I prefer 40-grain softpoints or hollowpoints.
If hunting edible game--anything from squirrels to turkeys--I much prefer loading the round DOWN somewhat, instead trying for every extra fps.
But whatever....
