[georgehutchison]

So heres where I am so far. I dissasembled another long m4 today to try this s120 spring. came out at 390 fps w/.20's so its not the spring.
Next I installed the g&p mechbox into the d-boys gun with the d-boys barrel and hop up. =390 fps.
so its not the hop up or barrel. Great seal in the hopup as i have allready checked it for leaks.

Next I installed the back to stock d-boys mechbox into the g&p AEG and it shoots 350 fps. Same readings as with the d-boys barrel and hop up.

I then installed a modify s120 in the stock d-boys mech box and got around 330fps in both G&P and d-boys guns.

So far i have narrowed it down to being some issue with the d-boys mechbox with a longer spring. Can't see how as it makes no sense at all. I think i will leave the d-boys mechbox stock spring in and just instal bushings and shim it.

As far as wanting higher fps, I use .28 ammo at our outdoor field and found that extra 50 fps gives me a small advantage in range. My G&P is fully done up and can handle 400 fps with no issues. I use it on semi auto only and run it more as a countersniper setup.

I agree that 350 fps is usually enough and I use many other guns shooting at that fps for most applications.
I am going to do a little research on d-boys and see if other players have done setups on thier mechboxs. I will post back