I just got this gun. My first airsoft gun by the way. I upgraded the spring, piston, and spring guide. The gun shoots 500 with 25g crossman bb's. I stock piston was a wreck. it has casting peices covering the oring in it, glad I changed it. I also used a wine cork as a barrel spacer. Worked very nicely. Now, when I shoot from 100', 1/3 of my shots are on the money, 1/3 are close, and the last 1/3 are all over the place. Is it the cheap bb's? Should I get a hop up or a TBB next? Also, I have been looking online for the cheaper alternative to the PDI hop up and I can't see to find it in stock anywhere. I cant remember what it is called, but I see some of you guys on here use it. Where can I get one? I dont want to pay $100 for a PDI.