You found an Interarms 9mm Czech ammo box in a hardware store??? It depends greatly on the headstamp and the box as to what kind of bullet it is. If it's a green box, and if the headstamp has a number in the 50's with some shape symbols, then it is steel core. This ammo is classed as "armor piercing" pistol caliber ammo by the BATFE and is illegal for licensed dealers to sell to anyone other than Government or law enforcement. You can see the list of restricted bullets on the BATFE's Federal firearms reference regulation guide" - section 17 of the general information section. In the mean time, pull one of the bullets and blowtorch the base of the bullet to see if a little lead melts out and exposes a steel core. If so, you might want to tell that hardware store owner that he's committing a felony by selling it to civilians, and that ignorance of the law is no defense (though he'll probably never get in trouble anyway). And what state are you in? If you're in CA, TX, IL, NJ, KY & Wash D.C. then it is illegal for you to possess it in any way unless you have a class 10 / 11 FFL license, or unless you are law enforcement. If you are not in one of those states, then it is still perfectly legal for civilians to own such ammo, and this stuff is bought & sold on Gunbroker regularly between civilians, but licensed dealers selling the stuff is still illegal in any state. This steel core stuff usually sells for a dollar per cartridge when advertised as "armor piercing 9mm" on Gunbroker, but it wasn't really intended as armor piercing, it's just a lead shortage thing - so they used steel instead for the cores. It will blast through body armor of course though, not to mention vehicle bodies.
Here's a pic of the green box that I am thinking of for steel core ammo, and the associated Czech surplus that was repacked into the boxes: