What do you think Marxists will be guarding, their own lives or warehouses of ammo?
The world is awash in civil wars in last few years. In each one of them government stocks of arms and ammo are raided by the rebels. This happens either because the government troops cannot be everywhere at the same time, or because the government soldiers are not that interested in dying for a dictator. In the end all this ammo is used against the government, and the government falls.
There is yet another interesting fact. In all those civil wars rebels have foreign support and are supplied with money and weapons and ammo. If a civil war happens in the USA, what countries will be on the side of the citizens? (This can be figured out by asking what countries will be on the side of the government.)
True, from the people I know in the military, if they let the military guard it, we will have access right away.Most of the military are patriots.