. . . I have never run across a business with a 30.06 sign. . . .
They're around, but the places that have compliant PC30.06 signs are not generally open to the public - examples would be the offices and factories of Dell, 3M, etc.
Some other businesses have
non-compliant signs - either citing an obsolete law, or saying something like "Security Notice - Concealed Weapons are Prohibited" . . . but of course, these signs have no meaning.
The one place I've noticed that had a sign citing PC30.06 was Half-Price Books . . . and considering it was on a single 8 1/2" x 11" sheet of paper, it was nowhere near being a "compliant" sign.