What does this cz58 spring do?

[suprathepeg]

Mine fell out and I don't know where it goes.

rifle has functioned flawlessly without it though.

 

[Kasat]

It sits on a trigger pin to increase the tension , absent on the milspec one and some other versions of this rifle.
Mine landed in the garbage long time ago but it's up to you what you are going to do with it. There is a scratched area at the bottom of your receiver just in front of the trigger hole , that's where the longer end of this spring sits.

 

[suprathepeg]

So basicly without the spring the trigger is lighter?

 

[Kasat]

Correct.

 

[aftermidnight]

i learn something new everyday...

 

[Curtton]

without the spring in the trigger it may cause another problem , at least increase wear on the SD :

http://www.canadiangunnutz.com/forum/showthread.php?t=169256