With the bolt handle lifted far enough to retract the bolt the was no real danger of firing the jammed cartridge. (Perhaps inless the trigger was pressed and the bolt handle driven downward) It is mechanically blocked. If it wasn't there would be all kinds of horror stories from people cycling the action roughly when chambering or extracting live rounds.
And my English / American translator is broken today. What does
"I’ve turned up to a match wondering why I couldn’t chamber a round, to find part of a bore guide in my chamber."
Mean? ~Muir