Sounds pretty normal for a new gun not to fully seat the bolt. Don't push the lever to force it, that will only cause problems if it doesn't want to seat on it's own. It will wear in gradually. The gun should be closed with a degree of authority, not slamming it shut, but not holding the bolt open and then softly closing the gun either. They are designed to be tight for some time and gradually wear in if they are properly closed.