So, I bought a TBB of EBAY for $40. 500mm stainless 6.01. I have no clue what kind it is, but it is the same cut as the stock barrel since it fits in the stock hopup. I sanded down the arm in the hop up and threw in a H-nub. WOW. At 100' I am hitting about 8 out of 10 shots within a 6" pattern. All the left and right fliers are gone. I still get an errant shot that sails on me. I am using .28's. I think if I increase the weight I should really be set. I also noticed and increase in FPS. I use a peice of foan that is roughly 2" thick and I generally could not get a bb through it, but now I have them poking out of the other side, not completely through. I am a believer now!