Sounds like a good indoors shooter. I have also noticed the new production Buck and Red Ryders seem to have a buzz to them. Something else you might try, is using some "tar" on a new spring instead of cutting it shorter. The tar damps vibrations and will in many cases lower the velocity, depending on how much is used (trial and retrial). PA supposedly now sells something called "Tune in a Tube", which is a sort of heavy grease similar to tar. This gives the option of going back to full power if you wanted to later on.
Here is the great thing... I still have parts from those B2-1s that I hacked and chopped. I have the parts to fix his.