Should I Get a New Spring?

[LazzurusMan]

So about 2 years ago I had my king arms sig rebuilt after I blew apart my piston head (I rushed building it and forgot to lock tight the thread).
She's currently firing about 320fps on 11.1 lipos .2g b's and a guarder sp100 spring (spring was fitted by shop).

If I wanted to get as close to 350 as possible, would a 110 spring do the job, or would it be too much? Pretty much all of the air seal components were replaced when the gun was worked on, so the spring is the only thing I can think of that would be preventing me from getting 340fps or more.
I'm going to a skirmish tomorrow and might be able to pick up a 110 spring and fit it during lunch, but I just wanted to check if it's more likely to be a problem elsewhere before I go ahead.

 

[ak2m4]

What's the inner barrel length and cylinder type?  If you're firing at 320fps with a Guarder sp100 then you've got some air leak somewhere.  You should be hitting around 360fps (of course depends slightly on the inner barrel / volume etc)

What FPS did it leave the shop with?

 

[Adolf Hamster]

worth checking the fps consistency on the chrono, as above no point whacking a stronger spring in there until you're sure that extra energy isn't just going to get lost in a leak somewhere.