Inner Barrel length -WE M4

[Neilbarker]

I’ve got a WE M4 with the standard barrel in it atm, I’ve got the barrel extension off and a mock suppressor on the front. However I want to shorten it and take the suppressor off, but in doing so, how much performance is lost in losing the barrel length? The NPAS can be adjusted for the FPS drop if any, but will the barrel length change effect the accuracy, outwith the normal consistency of gas guns? 

Cheers