If I am reading this correctly after July first no non-resident can have a magazine over 10 rounds for a long gun or 15 rounds for a hand gun in Vermont.
"Can a resident from another state bring a large capacity ammunition device to Vermont?
Until July 1, 2019, a nonresident is permitted to bring a large capacity ammunition device into Vermont provided such device is lawfully possessed by the nonresident and is to be used exclusively in an established shooting competition in Vermont. After July 1, 2019, this exception is eliminated."
New Vermont Gun Laws FAQs | Department of Public Safety
"Can a resident from another state bring a large capacity ammunition device to Vermont?
Until July 1, 2019, a nonresident is permitted to bring a large capacity ammunition device into Vermont provided such device is lawfully possessed by the nonresident and is to be used exclusively in an established shooting competition in Vermont. After July 1, 2019, this exception is eliminated."
New Vermont Gun Laws FAQs | Department of Public Safety