The idea is not really to keep the bolt from opening or the rifle from firing if the bolt is not fully locked. The latter will not happen because the firing pin retraction cam will prevent it. What the trigger interlock does is to signal the soldier that the bolt is not locked. He can then just tap the bolt handle down. Other cock-on-closing rifles (e.g., Model 1917, Arisaka) have the same feature.
If the trigger interlock were not present, the firing pin would drop to the retract stop and the soldier would have to recock the firing pin (impossible or difficult on most rifles) or operate the bolt to resume firing.
While seconds might matter in combat, that would rarely if ever be the case in civilian use, and the trigger interlock should not be needed in a sporting rifle.
Last edited by James K; September 5, 2009 at 10:42 PM.