I have a Tokyo Marui HK416D NGRS, and I am looking for an upgrade of spring for it. I have read online that there is no issue swapping in a stronger spring on stock internals so I do not have to worry about wrecking it, I am just looking for recommendations of springs. There does not seem to be a major selection of springs available, having myself only found these:
https://www.combatsouth.co.uk/cyclone-7-m100-spring-for-ngrs-series/
https://eagle6.co.uk/product/eaglesix-m100-spring-for-m4-ngrs-aeg
https://www.davescustomairsoft.co.uk/bespoke-airsoft-stel-tek-m100-spring-for-tokyo-marui-next-generation-recoil-shock-series
https://www.airsoftwholesaleuk.com/product/fps-m100-100m-s-steel-spring-for-tm-ngrs/
https://www.krale.shop/uk/spring-eagle-6-m100-for-tokyo-marui-ngrs/
I have also found this one which is stated as a TM next gen gearbox use, however from the picture you can see it is a non linear spring.
https://www.davescustomairsoft.co.uk/next-gen-hardened-steel-spring-m90-m100-m110
Due to the TM NGRS relying on multiple springs to operate as designed, the spring operating for pushing the piston in a linear spring, and these are also known to be shorter than other AEG springs. I am wondering if there is anyone with experience or has leads on good brand of spring for my scenario. Guarder, PDI and Prometheus do not seem to supply NGRS springs.
My intended goal is to squeeze out as much power out of the gun as possible, as Japanese limitations on AEG springs result in TM often running M85, so I wanted to upgrade to something more capable to fling heavier ammo. With possible changes later on such as inner barrel and buckig to aid this, for now I will just try a stronger M100 spring. I have had someone recommend eagle 6 springs but I am wondering if there is someone more informed on the topic to be able to shed some light on this for me.
Thanks in advance!