[Apache6]

Stateside in the U.S., major bases have a certain ammount of contingency ammunition which is really maintained to provide the initial combat load for forces mounting out for expeditionary operations. I will not state specific amounts but it's more then a couple combat loads (though it veries by type) for units assigned there with expeditionary missions.

There is also normally a fairly large amount of ammunition stored for training. A major combat unit goes through a lot of ammunitiion over a course of a year. The ammunition is normally ordered and delivered based on fiscal year (begining in October rather then Jan) training cycles.

At an absolote minimum, even a non deployable Marine unit gets ~ 400 rounds of 5.56mm for each Marine to conduct annual rifle range requalification and ~ 200 rounds of 9mm for each SNCO/Officer and junior Marine assigned a pistol to conduct annual pistol qualification.

Deployable combat arms units are allocated much more ammo.

There are several VERY large ammunition stockpiles on the east and west coast which are built near major ports to allow for then to be sent overseas, each also has rail and road access, built to allow them to receive munitions from the factories. Would also serve to allow it to be sent out.

Both the Army and the Navy (for the USMC) have contracted ammunition ships which contain large ammunition stockpiles which are designed to support major combat operations by brigade sized units. The Maritime Positioning Ships, contracted by USN in support of USMC land operations stock 15 days worth of ammunition for a Marine Expeditionary Brigade.