Soldiers and Heaven

The Life of the World (a publication of the LC-MS Seminary in Fort Wayne, IN) had the theme of chaplains for its current issue. An article titled "What does this mean?" discussed Luther's arguments that a soldier is not in peril of eternal damnation due to his vocation as a soldier. And I agree with this article. However, I cannot seem to rectify myself to full satisfaction the difference between soldiering in ancient times and the American methodology. Previous generations were conscripted (drafted in modern parlance) to fight when there was an enemy. The only other source of soldiers were mercenaries who fought for money. The modern American soldier is a "volunteer", which means they sign up for service without being directly "asked" to do so. While this is a proper vocation as it is an arm of the government emplaced by God, does the vocation take on a slightly less proper hue when the soldier is a volunteer versus a draftee? I don't think it would, but I can't seem to reason out the solution. Thoughts on the subject are welcomed.