I had two but now have three things to comment on.
1. Go to your local lumber yard or big box Home Depot type store and get some thin wallboard and some small screws and nuts. You can use peg board or 1/4" plywood. The peg board will already have the holes in it. Basically you can just put sides onto your storage rack and a couple of simple hinges on the front and a makeshift door with a padlock clasp. Mostly it's to keep curious eyes from bugging out. Cheap and easy and secures the stuff from small hands and big mouths.
2. Go to one of your friend's houses, not from your's, and make the calls to the local fire department, city planning office, and local P.D.. Make the calls anonymously as a general inquiry. Tell them you were thinking of getting into some target shooting or a Skeet and Trap league and someone told you that there were regulations or laws about how much ammunition you could have on hand at home. You can even tell them that there is a 3-day competition coming up and it was recommended that you have a few thousands rounds of ammo with you. If there is a law then a phone link will put them at someone else's house, not high road, but safer than not.
3. Your comment:
I am the one the organizes the monthly shots for my friends at the office and some buy ammo from me if they shoot one of my guns.
causes me some concern. According to your comment you are now an ammunition dealer of sorts, so stop doing that. Also, per your comment, you are now an organizer, which might saddle you with some liabilities. I'm not a lawyer, but I have been reading up in a bicycling law reference book recently about liability on organized rides, and if I read it right you might have some liability if you are in fact "organizing" the shoots. So, stop doing that and pass the baton to someone else.
I've got nothing else to say on this.
Take care, be safe, be smart.