M4 hop up spring replacement

[Hortons Heros]

I am working on an m4 and the spring at the front of the hop up is missing. I am wondering if anyone knows of a good replacement without having to order a whole unit. Something like a mechanical pencil or a dollar store toy with the same size spring.

[cetane]

A spring from a clicker pen can be made to work. My m4 had no spring for a long time and did not change the function of the gun. Once the mag is inserted it interlocks with the hop up so I don't see why really that spring is there

[Kos-Mos]

Dollar store, buy one of each cheap clicker pens.

I found the ones with clear/colored upper sections work most of the time.
You want the ink tube to be small for the right spring size.

[ybrik]

Just buy a spring about an inch long and insert it in the inner barrel till it reaches the hop-up. That's the way it is on an m-14 hop-up. I never knew this is possible, I saw some vid on youtube.

[Hortons Heros]

sweet guys, thanks