Came across this while looking up an answer for another post and remembered this post. It looks to me like if it depends on how much time you spend in your home in Maine. If you spend your summers here, then yes you are a resident per the ATF without having to establish a residency per MAINE law. Of course convincing an FFL how long you spend in your Maine house will be the problem in this situation.
From page 126 of this document:
http://www.atf.gov/publications/down...f-p-5300-4.pdf
27 CFR 178.11: MEANING OF
TERMS
An out-of-State college student
may establish residence in a State
by residing and maintaining a
home in a college dormitory or in a
location off-campus during the
school term.
ATF Rul. 80-21
"State of residence" is defined by
regulation in 27 CFR 178.11 as the
State in which an individual regularly
resides or maintains a home. The
regulation also provides an example
of an individual who maintains a
home in State X and a home in State
Y. The individual regularly resides in
State X except for the summer
months and in State Y for the summer
months of the year. The regulation
states that during the time the individual
actually resides in State X he is a
resident of State X, and during the
time he actually resides in State Y he
is a resident of State Y.