low fps on condor

I noticed the accuracy on my condor ss .25 was not what it used to be so i put it on the chrony and was only getting about 600 fps with jsb exact king 25.39 gr.I raised the dial up to 10 and only getting 670 fps. I have the talon tunes top hat wide open. Can anyone give me some ideas on what may be the problem? Thank you.