17 mach2 wont extract

[97guns]

i just took a FV mach2 out for the first time today and was unable to get a spent case extracted. it will extract a live round every time, does anyone know what might be the problem? im thinking that the chamber may need to be scrubed so i intend to try that before the next trip out. any other ideas of what it might be? tia

[82boy]

I would say that it is dirty. Give it a good scrub and see what happens.