The further we progress into Tim O'Brien's collection,
The Things They Carried, the more it seems that O'Brien is purposefully blurring the lines between the semi-fictional "truths" in the book and the reality of the events. Even though it appears that most (if not all) of the stories in the book are based on the actual experiences of O'Brien and Alpha Company, the reality he presents in the stories doesn't always reflect the facts of the their experiences. It seems to me that he does this as a way to get us (the readers) thinking about what actually matters in the stories, what we are supposed to pay attention to and what we are supposed to come away with.
In "How to Tell a True War Story," O'Brien says that a true war story has no moral, that there is no "lesson" that one shold take from a true war story. This really fits in with his presentation of the "truth" because in neing unusure whether or not the events O'Brien describes actually happened, the only thing that the reader can take from the stories are the feelings and emotions taht were conveyed rather than the actual facts. By keeping from us the reality of the stories, he is telling a "true war story." There are no morals or lessons to draw from the events themselves since there is always a possibility that O'Brien made them all up. However the factuality of the events doesn't change the experiences and sensory details that O'Brien is trying to convey.
One good example of this is in the story "The Ghost Soldiers," when O'Brien is describing the conditions in which the events of the story are taking place. He says "you're not human anymore. You're a shadow. You slip out of your own skin like molting, shedding your own history and your own future, leaving behind everything you ever were or wanted or believed in. You know you're about to die" None of that is factual detail from the story, but it does just as good of a job conveying the feelings that O'Brien wants us to experience.
In the end I think Tim O'Brien just doesn't want us to get hung up on the details of his story, like he described in "How to Tell a True War Story," in the bit about the woman that always comes up to him afterwards to comment on a particular detail that really made the story for her. Even though those seens are there to evoke emotions, O'Brien doesn't want readers to take the facts of the scenes at face value, that would be missing the point, he simply wants us to understand the experiences and the feelings of the stories.