d cap bearing the markings is damaged and requires replacement.
Q2: May a Federal firearms licensee repair a silencer by replacing worn or damaged
components?
A: A person who is licensed under the Gun Control Act (GCA) to manufacture firearms and who has
paid the special (occupational) tax to manufacture National Firearms Act (NFA) firearms may replace a
component part or parts of a silencer. Repairs may not be done if they result in removal, obliteration, or
alteration of the serial number, as this would violate 18 U.S.C. § 922(k). If a silencer part bearing the
serial number, other than the outer tube, must be replaced, the new part must be marked with the same
serial number as the replacement part.
The term "repair" does not include replacement of the outer tube of the silencer. The outer tube is the
largest single part of the silencer, the main structural component of the silencer, and is the part to which
all other component parts are attached. The replacement of the outer tube is so significant an event that
it amounts to the "making" of a new silencer. As such, the new silencer must be marked, registered and
transferred in accordance with the NFA and GCA.
...
Persons other than qualified manufacturers may repair silencers, but replacement parts are "silencers" as
defined in 18 U.S.C. § 921(a)(24) that must be registered and transferred in accordance with the NFA
and GCA.