Looking into doing some upgrades to your AEG? Watch Fox Airsoft talk about AEG upgrade springs in this video... "Modifying or disassembling your airsoft gun voids your warranty from us. Consult professional help when performing upgrades or do so at your own risk.

FPS is a limit not as goal!

If you can't verify the results with a chrono, undershoot your target FPS with a spring rating lower. Better to be under than over if you're not able to do the work to change the spring yourself.  Your local tech should be able to suggest the best spring based on their experience with the brands and batches of springs they have. Some batches clock in higher than advertised and that is very much a thing. We like ASG and Modify for high quality springs, though the CNC Products ones we carry are a bargain and do the job too.

TL;DR what spring do you need:

• For most CQB fields, 1J or 350fps measured with a .20g BB = M100 spring or less
• For most outdoor fields, 1.5J or 400fps with a .20g BB or 340fps with .28g or less than 320fps with .32g

Downgrading reduces stress and wear and tear. Upgrading increases wear and tear. Upgrading a gun to shoot harder than stock may require an upgraded battery and/or motor."