EAJ said:
Wouldn’t a replacement firearm, with a new S/N, necessitate another background check through an FFL dealer?
No.
27 CFR 478.124:
§ 478.124 Firearms transaction record.
(a) A licensed importer, licensed manufacturer,
or licensed dealer shall not sell or
otherwise dispose, temporarily or permanently,
of any firearm to any person, other
than another licensee, unless the licensee
records the transaction on a firearms
transaction record, Form 4473: Provided,
That a firearms transaction record,
Form
4473, shall not be required to record the
disposition made of a firearm delivered to
a licensee for the sole purpose of repair or
customizing when such firearm
or a replacement
firearm is returned to the person
from whom received.
and 18 USC 922 (a)(2):
§ 922 Unlawful acts.
(a) It shall be unlawful—
(2) for any importer, manufacturer,
dealer, or collector licensed under the
provisions of this chapter to ship or
transport in interstate or foreign commerce
any firearm to any person other
than a licensed importer, licensed
manufacturer, licensed dealer, or licensed
collector, except that—
(A) this paragraph and subsection
(b)(3) shall not be held to preclude a
licensed importer, licensed manufacturer,
licensed dealer, or licensed collector
from returning a firearm
or
replacement firearm of the same kind
and type to a person from whom it
was received; and this paragraph
shall not be held to preclude an individual
from mailing a firearm owned
in compliance with Federal, State,
and local law to a licensed importer,
licensed manufacturer, licensed
dealer, or licensed collector;