Can't Close Bolt on my No.4 Mk 1

[Peter Laidler]

Ah, yes, but this small movement of the cocking piece (and striker) when you LIFT the bolt handle initially is nothing to do with a 'cocking' action. It is a mechanical safety feature. All it does it ensure that the striker is positively withdrawn from the front face of the breech. Because the stud on the cocking piece is now raised from the LONG cam groove to the SHORT cam groove, it ensures that during the remainder of the movemants and actions of the bolt, the striker can NEVER protrude through the face of the bolt. Never that is, until you squeeze the trigger.

This is why it is of critical safety importance that you immediately reject a cocking piece that has a broken cam stud