No guns signs
No gun signs do not have the force of law on private property, except in establishments that serve alcohol.
"Public establishment" means a public building; not private property that is open to the public. 13-1302 only applies to the government, not private entities.
You may not enter any "public establishment" (public buildings) or a public event carrying a firearm after a "reasonable request" by the operator not to (13-1302). Storage, usually lockers, must be provided (13-3202.01) This does not apply to private property unless they serve alcohol on-site (see below).
You cannot consume alcohol at an establishment that serves alcohol, you cannot possess a firearm on the premises, and signs have the force of law even for concealed weapon permittees. Without properly posted signs, a permittee can carry concealed. 4-229 and 4-244
More about this tomorrow.
Employee protection/parking lots
Generally, a property owner, tenant, public or private employer or business cannot prohibit a person from lawfully transporting or storing a firearm in a locked vehicle out-of-sight. 12-781
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