Changing of Numbers in the New Edition of "The Things They Carried"

As we discussed in class, O'Brien changes many of the numbers in the new version of the novel, while keeping all other words and details this same.  This is rather peculiar, and upon first glance there seems to be no reason behind these changes.  While some could argue that O'Brien made these changes as somewhat of a gimmick, I believe he had purpose in his actions.  Many of the number changes by O'Brien were changed into larger numbers, possibly to illustrate just how much these men had to carry in their bags in Vietnam.  It also plausible that O'Brien chose these new, more exact, numbers to appear more realistic, instead of using nice round numbers like in the original edition.  In reality, there is no way to know exactly what O'Brien's methodology was in making these very subtle changes, but one thing we do know is that O'Brien certainly had a purpose. What that purpose was is something I'd like to know.