Ics sig 552

[Fat_P]

Hello I have an ICS SIG 552 and I changed the inner barrel for a Madbull Black Python Vers.II 6.03mm to 247mm as the store told me that it was done for a SIG 552. But my original barrel is 260mm. A difference of 13mm. I do not know if his mind for my performance on the fps.

Because at the beginning with the barrel and the original spring I have 350fps. And with tighbore Madbull Madbull Red bucking a 60 ° and original nub I have 358fps. I think it is very little for the upgrade I've done. And especially its normally should give me 15-20 fps more. It you a possibility to get the fps I'm supposed to do with the upgrade I've done. Thank you