Vibrating spring.

[league 4]

On a bolt action... I can see that as being easier for the tape staying on than an automatic AEG. I've never tried it myself but it seems like it'd come loose after repeated use on full auto. That's really weird about the vibrating problem though, I've never heard of it before.

[Jester316]

Putting an O-ring between the spring and the spring guide is worse. The spring will chew the thing up and than you have little bits of rubber in the gearbox. Wrap it around the back of the spring, where the windows are cut out in the gearbox. That way you can easily check it and fix it if need be.