From what few numbers I've seen posted for the 240 they seem to run from the high 400's to the mid 500's depending on pellet weight. As I mentioned earlier, mine is shooting the 7.33gr AA Falcons at about 540fps. The 240 is definitely no speed demon, but it has enough juice and accuracy to protect a feeder from house sparrows and starlings, as long as you keep the distance under 20yds.
Mine has a tiny bit of buzz/twang, but it's not too bad. Unlike most Diana springers, my 240 had plenty of lube inside, almost too much. If you decide to keep it, definitely do a tear down and polish the spring ends and give it a proper lube job. Like most springers, mine responded pretty well to that.
Have fun with it! And I'll be watching to see how the accuracy is with yours.
"You've come far, pilgrim."-------"Feels like far."
"Were it worth the trouble?"-----"Ah, what trouble?"