Constructive possession. Doesn't specifically say anything about held out of state, but under the partial/full payment I believe that it would be covered. CCDL has a nice affidavit form for mags and firearms.
Q: I purchased an assault weapon and/or large capacity magazines prior to April 4, 2013, but they were not delivered until after April 4, 2013. May I legally take possession
of them now?
A: Yes,you are in “constructive possession” provided that:
Pursuant to a lawful purchase
(i) a contract for sale was made between the parties prior to or on April 4, 2013 for the purchase of the assault weapon, or
(ii) full or partial payment for the assault weapon was made by the purchaser to the seller of the assault weapon prior to or on April 4, 2013, and
(iii) you can present a writing sufficient to indicate (i) or (ii); or
Actual possession or constructive possession is established by a written statement made under penalty of false statement on such form
prescribed by the Commissioner of Emergency Services and Public Protection.
If you purchased an assault weapon with large capacity magazines on a 14 day wait list and your dealer obtained a STN number prior to or on April 4, 2013 and the 14 days did not expire until after April 4, 2013, your dealer may lawfully transfer the weapon to you, with any accompanying large capacity magazine s despite the fact that the transfer is after the effective date of the Act.