Let me start by saying that this is a sparatic problem that has no consistency as to when it happens. It was a GI custom gun (which may be the problem to begin with). I haven't touched anything internally. The only changes to it were the parts that GI put in to make it "custom".
The problem that I am randomly having is with the spring not being locked in place when I pull back on the bolt. The one thing that seems to be able to correct the problem when it happens is rotating the end of the bolt counter-clockwise. Something else that I had noticed was sometimes tightening the screw at the end of the bolt seemed to help a little bit in correcting the issue.
Here is a link to the gun I am talking about if you need to see it, or the upgrades that went into it:http://www.airsoftgi.com/product_info.p ... ts_id=7962
If anyone knows of how to fix this issue it would be greatly appreciated, thanks.