I don't have an m18 handy but many bolt rifles will "fire" without the bolt fully closed. By this I mean pulling the trigger will first fully close the bolt as the firing pin moves forward but it does reduce the velocity of the firing pin. The only 2 rifles I have handy are a 700 Rem and a Ruger 77. Both allow this. I did not try with a live primer but will next time I am at the range.
pavementends
