Spring for my M4
 

good day gents, i have a spring issue with my M4.

M4

Version 2 mechbox

Ported Cylinder

Systema helical gears

TM Eg1000 motor

Current spring (Unknown brand and %) clocks the fps at 395fps :banghead:



What kind of spring should I buy in order to shoot 350-360fps Max.?:D

thank you for your help;)

M100 should get you around that velocity.

I've used this chart for quite awhile now when upgrading springs. I've found my results vary a little bit but are pretty close to the numbers here.

http://www.mechbox.com/data/airsoft-spring-comparison-chart.html

Wow, that chart is definitely not right, at least for Systema springs.

Check this chart for more options/more accurate results

http://www.airsoftcanada.com/SpringChart.php

A lot depends on other factors with your setup...and how tight all the air seal/compression is.

On some AEGs, with various setups (you don't specify what kind of spring guide, piston head and inner barrel you have...which influence the final FPS range)...have resulted in 300-340fps with a Modify S90 (again...lots to do with other parts in the setup)...and 350-375-ish with a Modify S100 spring.

So...I'd recommend getting a Modify S100 and a S90. Springs are cheap, they don't go bad....but if the one you buy is too hot, it sucks to be stuck making a separate order for another.

Or you could try a Modify S100 and if it's still to hot, turn the spring around. It might drop it down enough. But I've had mixed results from doing this...everything from a 10fps to 40fps drop (pretty much a complete wild ass guess)

Tyson

I've never compared it to systema springs, for the springs I've run it's been pretty darn close. Sorry to spread mis-information though. Just based on my results I felt it to be a good read. There's an older spring chart too.. don't know if that's any better.