WTF?? So they had you using it as a club?
In the cases where we were issued weapons and no ammo, it was during training exercises. Sometimes the higher-ups just want you to lug around the weapon for the sake of lugging it around, even though they don't go through the motions of issuing ammo.
I remember one occasion where our unit was conducting roadblock and search (external - for IEDs) training over the course of a week. We were completely contained on a military base and we were stopping traffic, etc (mostly military but there were some civilians mixed in as well). During that exercise we were issued weapons and no ammo. We were told to insert empty magazines. So I guess the higher-ups figured we weren't going to have any issues anyway and if we did, then yeah - guess we had to use them as clubs.
I also remember once; my unit having all our ammo confiscated by civilians. Our C-130 had broken down and the Army chartered a civilian aircraft to get us where we were supposed to be. The civilians at the airport made our commander collect all our ammo and presumably store it elsewhere about the plane. Not that that is any big deal - I understand the rationale there.
We sure did get some strange looks from the civilian passengers waiting to get on their planes though! An entire unit tromping through the airport in all our combat gear and weapons while en-route to our special 'holding area' where we waited to get on the civilian plane.
Anyway, just adding this last story in for additional information - oh, and this all took place in the mid-90's with the Army.