I've been building a custom ca 25 for about a year just tinkering with it. It has had almost every part in it changed. My main problem is that it is not very consistent. I do not know how to make its Fps more consistent. For a while I had a silent piston head in it, but I removed that because I thought it would solve the problem. It helped a good amount, but I still can't get it fine tuned how I would like. I haven't chronoed it since I took out the silent piston head, but it had started with low Fps and as I pulled the trigger, it got faster. Each shot would have a higher Fps than before. This is still a slight problem, but not as noticeable. I have a guarder sp170 spring in it. I guess that the longer gearbox decreases the Fps that the spring could put out, but I believe my gun is maxing out around 500. Is there any way I could better the consistency? I have a replaced piston in it with the piston head from a magpul Masada. It has the stock cylinder head. Ca super torque gears for sr25. Amp t5000 motor. Systema hop bucking. Stock hop unit. Ca 6.04 barrel 509mm. And I assume the 11.1 30c lipo doesn't make a difference. It is cut to semi only.