Replying to Airsoft Help PLEASE!

I have a JG Bar-10. Stock it gets 400 fps with .2g bb's

after i modded it it got about 450 fps with .2's for a long time. i havent used it in awile and just shot it again with .2's and it shoots so slow that if shot level the bb falls to the ground in about 15'. i've adjusted the hop up and i am getting no effect. The spring/cocking feel feels the same as before so i am really confused. The bb's load just as consistently too.