Looking at the video it appears you can see a bit of the bolt shaft/probe so try fitting an oring over the bolt so the oring sits on the bolt shaft & just compresses when you close the bolt, its how the S400 series does it. This will help tension the cocking pin in its housing.
It also appears that the bolt head sits against the stock which may be stopping the bolt from fully closing, if you remove the action from the stock does the bolt head sit lower & if you fire it does it still flip up. If this is the case then the bolt needs loosening on the shaft & lifting up so it closes fully without quite touching the stock
Last edited by Scooby; 11th August 2012 at 03:20 PM.