Wells m401 spring help

Looking to put a 1.4 uneven spring into my wells but it seems to be too long and the motor can’t do the full cycle by pulling it back, any suggestions? And yes I have a mk box with all the goodies including a high torque/speed motor

The wells 401 has a shorter spring, Its around 145mm so you need to either get one for it or cut the one you have shorter.

I have a dremal, I hope cutting it to size will fix the problem


It could also be the buffer tube retaining screw is too long ?

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Already cut it down but only had the gearbox and handle attached to test

Ok cool, if a spring is to long the compressed length can also be to long and the piston can not go all the way back especially with an unequal spring.
If you have an upgraded motor it should have no issues pulling a 1.4mm spring

Sweet thank you for your help once again @Rattler

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