IIRC the Vixens were advertised
guaranteed to exceed 600 fps in .22 and 800fps in .177 !!! It doesn't state the weight of the pellets used ;-). I have also read (Dennis Hiller books?) the if the main spring doesn't break within the first hundred shots it will last a lifetime.
Did yours have a broken spring? Didn't they also come with a little bronze medallion?
Good thread.
ATB
Ian