You may be a bit disappointed with the TF97. It may shoot at or above the 750 mark initially due to detonation from whatever lube or oil the maker has put in the compression chamber, either from the manufacturing process or as an anti corrosion agent, but once it stops power will drop off. In addition, after a time the spring will take a set and produce somewhat less power. Most users report longterm velocities in the 650 range. Almost every air-gun maker uses hyped-up velocity numbers to sell guns. Some use super light weight pellets, some get the number by adding a bit of oil to induce detonation, some (like a few Chinese models) seem to be just outright deceptive.
Even so, 650 is plenty for whacking squirrels out to 25 yards, especially in .22. The Brits have been doing it for years with a 12 fpe limit. Look at the Leapers line of scopes, they seem to be a very good value for a small amount of cash. Don't skimp on mounts, as a cheap mount will render even an expensive scope useless.
