...hmm.....if youre pushing those jsb's in .20 cal , that means your chrono-ing less than 610 fps.........if it were mine (5mm r9) , i would have went the other way , and put the pg2 powerup kit inside....and no matter what , i'd use ftt pellets (damn things are $20 / tin now)....after about 200 shots , mine got a cloverleaf (usually) from a rest at 35 yards , near consistent 800 fps.....r9's love ftt pellets ! i would also get some dovetail mounts (bkl 257 rings - $20 at pyramyd) ... or even cheaper centerpoint mounts from academy sports stores would do fine on your detuned r9...my .20 r9 goldfinger vortek and my .177 walther lgv got about the same size groups out to 45 yards.....but the .20 caliber phenomenon shines best between 40-65 yards with my airguns.. https://www.youtube.com/watch?v=CwCD6flzghI