Take that other spring with you to an Ace hardware. My Ace has a really good selection of springs. You will have to clip the new spring shorter. That same spring took off on me when I had my PP700 apart. I heard it get sucked up in my vacuum a couple days later. After some digging through fuzz, I found it.
Good sources of springs for trigger groups-ball point pens and cigarette lighters. I would find a longer than needed spring and cut it instead of stretching a shorter spring. I believe you may have more consistent performance that way.
Hey guys ....nice video !! Will be handy to have around. Now...if you go to to the "systems" logo in the lower right hand corner of the video and click on "close caption" then translate...you choose your language and you get the commentary in "closed caption". Sweet !!