The pistols shoot at lower velocity than rifles, this one is spec'd at 540fps, similar to the velocity of a precision 10m rifle. So your 7.6gr pellets aren't a bad place to start.
Every new gun is an experiment with new pellets to see what it likes, have fun! Some you might start with:
Crosman Premier 7.9gr (the Walmart variety - the most convenient, not always the most consistent)
JSB Exacts
Air Arms - whatever they sell in that weight range
H&N Field Target Trophies 8.64gr
RWS Hobby available in both 7 and 8.4gr. These are wadcutters, nice if you're using the pistol to punch paper targets. Not expensive, but decent pellets.
There are a bezillion other pellets available in .177 to play with as well. The fun part of this hobby is testing all the cheap ammunition!!!