To eliminate the confusion about transportation in Illinois I think it's best to post the law as follows:
(720 ILCS 5/24‑1) (from Ch. 38, par. 24‑1)
(Text of Section from P.A. 94‑72)
Sec. 24‑1. Unlawful Use of Weapons.
(a) A person commits the offense of unlawful use of weapons when he knowingly:
(4) Carries or possesses in any vehicle or concealed on or about his person except when on his land or in his own abode or fixed place of business any pistol, revolver, stun gun or taser or other firearm, except that this subsection (a) (4) does not apply to or affect transportation of weapons that meet one of the following conditions:
(i) are broken down in a non‑functioning state; or
(ii) are not immediately accessible; or
(iii) are unloaded and enclosed in a case, firearm carrying box, shipping box, or other container by a person who has been issued a currently valid Firearm Owner's Identification Card;
The exception (i) or (ii) are the only legal ways to transport without a FOID card. Illinois does not issue them to non-residents. So, this would apply to all non-residents.
As to if exception (iii) allows a loaded magazine in the case here is some information from the Illinois State Police website FAQ:
Isit legal to have ammunition in the case with the firearm?
Yes, so long as the firearm is unloaded and properly enclosed in a case.
Case law has supported that a loaded magazine outside the gun is ammunition. Not a part of the firearm that would make it loaded.
As to what is a proper case:
What constitutes a legal "case" for transporting a firearm?
The Criminal Code refers to "a case, firearm carrying box, shipping box, or other container." However, the Wildlife Code is more specific, defining case as "a container specifically designed for the purpose of housing a gun or bow and arrow device which completely encloses such gun or bow and arrow device by being zipped, snapped, buckled, tied, or otherwise fastened with no portion of the gun or bow and arrow device exposed."
However local law can be stricter, and some communities have banned handguns completely.While passing through thesecommunitiesthe federal guidelines for interstate transportation are the only defense against prosecution. The ISP websitehas a database of local firearms laws, but unfortunately it doesn't have county codes listed.