[MGunner]

Well the SPR 250% is a 530 FPS spring.

So maybe the 150% or 200% is a ~500FPS

 

[MGunner]

Im pretty sure the SPR series is the 13mm ones, I would tell you but Im lacking the right measuring tools

I would go with the SPR 200%. It shoulkd be right where you want it. My 250% is 530.

EDIT:

http://www.x-fire.org/etop/bolt_sp_thicker.html

I knew I had that in my book marks some where!