S&T Kar98k vr firing issues.

Alright lads, had a blast at the Frontline WW2 game but my rifle has dropped a bollock!

 To fire it i have to raise the bolt, pull it back as normal. But then the only way to get it to ( sometimes ) fire is to drop the bolt before pushing it forward. Someone had a similar issue and cured it by liberally lubing it but this didn't work for me ( missed so many kills because it wouldn't fire although BB was chanbered ).

Any pointers would be a great help!