                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 05-10153
                Plaintiff-Appellee,
               v.                            D.C. No.
                                          CR-04-20100-RMW
RAMON ROMERO-MARTINEZ,
                                              OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
         for the Northern District of California
       Ronald M. Whyte, District Judge, Presiding

                  Argued and Submitted
       February 16, 2006—San Francisco, California

                   Filed April 25, 2006

  Before: J. Clifford Wallace, Michael Daly Hawkins, and
             Sidney R. Thomas, Circuit Judges.

                Opinion by Judge Wallace




                           4623
4626         UNITED STATES v. ROMERO-MARTINEZ


                        COUNSEL

Amanda K. Ruiz, Federal Public Defenders, San Jose, Cali-
fornia, for defendant-appellant Ramon Romero-Martinez.

Merry Jean Chan, Assistant United States Attorney, Oakland,
California, for the plaintiff-appellee.


                         OPINION

WALLACE, Senior Circuit Judge:

   Romero-Martinez appeals from his sentence of fifty-four
months imprisonment and three years supervised release. He
challenges the imposition of a two-level sentencing enhance-
ment under section 2K2.1(b)(4) of the United States Sentenc-
ing Guidelines (Guidelines) for possessing a firearm which
“had an altered or obliterated serial number . . . .” We have
jurisdiction pursuant to 18 U.S.C. § 3742(a) and 28 U.S.C.
§ 1291, and we affirm.
              UNITED STATES v. ROMERO-MARTINEZ             4627
                               I.

   The facts of this case are relatively simple. On May 8,
2004, Salinas Police Department officers responded to a
reported “brandishing of a weapon” at a restaurant and bar.
One of the officers saw Romero-Martinez in the men’s rest-
room and ordered him to stop moving and place his hands in
the air. Romero-Martinez did not comply and instead walked
into one of the stalls. He retrieved a black pistol from his
waistband and discarded it. Romero-Martinez then exited the
restroom and surrendered to the officers.

   The officers found a loaded 9mm model 19 Glock semi-
automatic pistol near the restroom wastebasket. Ordinarily,
such weapons have three serial numbers: one engraved on the
slide, one on the barrel, and a final number cast as a metal
plate affixed to the frame of the weapon. This particular pistol
was missing the serial number on the frame entirely and the
serial numbers on the slide and barrel had been ground off.

   Because of the timing of the proceedings, the procedural
posture is somewhat unusual. Romero-Martinez was indicted
for being a felon in possession of a firearm in violation of 18
U.S.C. § 922(g)(1) on June 16, 2004 and pled guilty on
August 3. Shortly after the indictment was handed down, the
Supreme Court released its decision in Blakely v. Washington,
542 U.S. 296, 313 (2004) (“every defendant has the right to
insist that the prosecutor prove to a jury all facts legally
essential to the punishment”). Romero-Martinez refused to
admit that the serial numbers on the gun had been “altered or
obliterated,” which would support a two-level enhancement
under section 2K2.1(b)(4) of the Guidelines. As a result, the
district court held a jury sentencing trial to determine whether
Romero-Martinez’s gun possessed a serial number that had
been “altered or obliterated.”

   At the sentencing trial, the judge instructed the jury that
“ ‘[a]ltered’ means to have changed or made different. ‘Oblit-
4628          UNITED STATES v. ROMERO-MARTINEZ
erated’ means to have removed completely or erased.”
Romero-Martinez objected to this instruction and instead pro-
posed an instruction based on the American Heritage Dictio-
nary that defined “ ‘obliterated’ as ‘To do away with
completely so as to leave no trace. To wipe out, rub off, or
erase (writing or other markings).’ ” On appeal, Romero-
Martinez challenges the inclusion of “removed” within the
definition of “obliterated.”

   Romero-Martinez also sought an instruction that the jury
could not consider the slide and barrel as part of the “firearm”
in determining whether the gun had an altered or obliterated
serial number. The district court disagreed and stated, “I think
the firearm as a whole is the three items when they’re put
together, so I’m satisfied [with] the instruction . . . .”

  The jury found, beyond a reasonable doubt, that the gun
possessed an “altered or obliterated” serial number. The jury
did not specifically indicate which serial number it believed
was altered or obliterated.

   Romero-Martinez moved for a judgment of acquittal on the
grounds that the serial number on the frame did not qualify
because it was attached by means of a metal plate, which
allegedly did not comply with federal law, and that the slide
and barrel were not part of the “firearm” under federal law.
The district court denied the motion.

   Before the district court sentenced Romero-Martinez, the
Supreme Court filed its decision in United States v. Booker,
543 U.S. 220 (2005). In its remedial holding, the Court sev-
ered the mandatory aspect of the Guidelines and rendered the
Guidelines “effectively advisory.” Id. at 245. Under this sys-
tem, the jury trial was not necessary and Romero-Martinez
thus received the benefit of a higher government burden of
proof on the factual issues.

   At sentencing, the district court recognized that the Guide-
lines were advisory but stated it would “look very hard at the
              UNITED STATES v. ROMERO-MARTINEZ             4629
Guidelines because there is the congressional goal of unifor-
mity in sentencing, among others.” The district court then
applied the two-level enhancement under section 2K2.1(b)(4).
The resulting Guidelines calculation generated a sentencing
range of 51-63 months. The district court sentenced Romero-
Martinez at the low end of the range to 54 months imprison-
ment, to be followed by three years of supervised release.

                              II.

   Much of this appeal is controlled by our recent decision in
United States v. Carter, 421 F.3d 909 (9th Cir. 2005). There
we held that “for the purposes of Guideline § 2K2.1(b)(4), a
firearm’s serial number is ‘altered or obliterated’ when it is
materially changed in a way that makes accurate information
less accessible.” Id. at 910. We further stated that the purpose
of the enhancement is “to ‘discourage the use of untraceable
weaponry.’ ” Id. at 914, quoting United States v. Seesing, 234
F.3d 456, 460 (9th Cir. 2001). “This purpose is advanced not
only by punishing those who possess untraceable firearms,
but also by punishing those who possess firearms that are
more difficult, though not impossible, to trace . . . .” Id.

    In Carter, we based our definition in part on the First Cir-
cuit’s decision in United States v. Adams, which held that
“anyone can see what Congress was getting at in the statute.
. . . [T]he statute aims to punish one who possesses a firearm
whose principal means of tracing origin and transfers in
ownership—its serial number—has been deleted or made
appreciably more difficult to make out.” 305 F.3d 30, 34 (1st
Cir. 2002).

   [1] Thus, the focus of the enhancement is whether the
action in question makes “accurate information less accessi-
ble” and whether it makes the firearm more difficult to trace.
Carter, 421 F.3d at 910. With this background, we turn to
Romero-Martinez’s individual arguments. Because we do not
know which serial number the jury relied upon in reaching its
4630          UNITED STATES v. ROMERO-MARTINEZ
verdict, we consider all of Romero-Martinez’s arguments to
determine if reliance on any of the three serial numbers would
have been legally erroneous.

                              III.

   Romero-Martinez first contends that the district court erred
by giving jury instructions that included “removed” within the
definition of obliterated. We review de novo the district
court’s interpretation and application of the Guidelines. Car-
ter, 421 F.3d at 911. We similarly review de novo whether a
district court’s instructions misstate the required elements. See
United States v. Phillips, 367 F.3d 846, 854 (9th Cir. 2004).

   [2] In Carter, we held that “a firearm’s serial number is
‘altered or obliterated’ when it is materially changed in a way
that makes accurate information less accessible.” 421 F.3d at
910. The district court’s instruction that “ ‘[o]bliterated’
means to have removed completely or erased” easily falls
within the definition established by Carter. Moreover, “re-
moved” falls comfortably within dictionary definitions of
“obliterated.”

   [3] Black’s Law Dictionary defines “obliterate” as “to
remove from existence; to destroy all traces of.” Black’s Law
Dictionary 1106 (8th ed. 2004) (emphasis added). Webster’s
Third New International Dictionary includes a number of def-
initions for obliterate, several of which contain “remove.” See
Webster’s Third New International Dictionary 1557 (1981)
(defining “obliterate” as “1: to remove from significance and
bring to nothingness: . . . b: to remove utterly from recogni-
tion . . . c (1): to remove from existence . . . (2) to cause to
disappear . . . remove . . . .”) (emphasis added). The American
Heritage Dictionary, upon which Romero-Martinez places
great weight, defines “obliterate” as “[t]o do away with com-
pletely so as to leave no trace.” American Heritage Dictionary
of the English Language 1248 (3d ed. 1992). Although this
definition does not directly use “remove,” it is clear that “re-
              UNITED STATES v. ROMERO-MARTINEZ              4631
moved completely,” the language used in the jury instruc-
tions, meets this definition. Thus, all of these dictionaries
support inclusion of “removed completely” within the defini-
tion of “obliterated.”

                              IV.

   Romero-Martinez next makes three arguments asserting
that this particular gun does not qualify for the enhancement.

                               A.

   Romero-Martinez first argues that the serial numbers on the
slide and barrel do not qualify for the enhancement because
they do not fall within the federal definition of a “firearm.”
Romero-Martinez contends that the slide and barrel are not
part of the firearm because they may be detached from the
gun and are not part of the “frame or receiver” of the weapon.

  [4] The applicable definition of a “firearm” is set forth by
18 U.S.C. § 921(a)(3), which provides in part:

    (A) any weapon (including a starter gun) which will
    or is designed to or may readily be converted to
    expel a projectile by the action of an explosive;

    (B) the frame or receiver of any such weapon;

    (C) any firearm muffler or firearm silencer; or

    (D) any destructive device.

    Such term does not include an antique firearm.

The definition is set forth in the disjunctive and therefore any
device meeting any of the definitions qualifies as a firearm (if
it is not an antique). “Destructive device” is further defined in
18 U.S.C. § 921(a)(4) and does not apply to the gun Romero-
4632          UNITED STATES v. ROMERO-MARTINEZ
Martinez possessed. While it is true that the slide and barrel
would not fall within definition (B) as they are not part of the
“frame or receiver,” it is clear that the slide and barrel fall
within definition (A). Both parts are necessary to operate the
weapon, and without them the gun cannot “expel a projectile
by the action of an explosive.” As such, it would be coun-
terintuitive to exclude these components from the definition
of firearm when they are necessary to complete the very
action that makes a gun a “firearm” under part (A). Thus, at
least when assembled as a functional weapon, the slide and
barrel are part of a “firearm” under federal law.

   [5] Under Romero-Martinez’s interpretation, the only
objects meeting the federal definition of “firearm” would be
those incapable of firing a projectile by themselves. Congress
did not intend such a limitation. We hold that, under 18
U.S.C. § 921(a)(3), both fully assembled guns, as well as
major components of guns (i.e. the frame or receiver), qualify
as “firearms.” As such, altering or obliterating serial numbers
on these components, at least when assembled as a functional
weapon, qualifies for an enhancement under section
2K2.1(b)(4).

                              B.

   Romero-Martinez next argues that the serial numbers on
the slide and barrel do not qualify for the enhancement
because they are not required by federal law. This argument
is foreclosed by Carter.

   [6] Carter held that a serial number was “altered or obliter-
ated” when “accurate information [is made] less accessible.”
421 F.3d at 910. Carter thus focuses on whether the informa-
tion was accurate, not whether it was required by federal law.
There is no argument in this case that the serial numbers on
the slide and barrel were not accurate information.

  Furthermore, we held in Carter that the purpose of the
enhancement is “to discourage the use of untraceable weapon-
              UNITED STATES v. ROMERO-MARTINEZ             4633
ry.” Id. at 914 (internal quotations and citation omitted). This
requirement is satisfied if the firearm is made “more difficult,
though not impossible, to trace . . . .” Id. The removal of the
serial numbers on the slide and barrel clearly made the
weapon more difficult to trace. Under Carter, this is sufficient
to qualify for the enhancement.

   [7] The issue of whether a serial number was required by
federal law is therefore not relevant to either Carter’s stan-
dard or the enhancement’s purpose. Removal of “non-
required” serial numbers removes accurate information,
makes a firearm less traceable, and is not indicative of any
lesser culpability. Mandating that a serial number be required
by federal law would allow many criminals to escape liability
under the enhancement even where they both intend to render
a gun less traceable and succeed in doing so. The enhance-
ment’s reach is not so limited.

   Romero-Martinez tries to escape this logic by raising hypo-
thetical reductio ad absurdum examples such as where a man-
ufacturer might tape a paper serial number to the firearm.
Although our holding on this issue will need to await a case
involving similar facts, we can address the argument. We are
unpersuaded that these examples would qualify as part of a
“firearm” under federal law because these “components,”
unlike the slide and barrel, would not be necessary for the gun
to “expel a projectile.” Therefore, they likely would not qual-
ify under 18 U.S.C. § 921(a)(3)(A). Of course, our decision
does not foreclose our court from recognizing common-sense
exceptions should such extreme circumstances present them-
selves in future appeals.

  Romero-Martinez essentially asks us to impose a new
requirement for the enhancement that is contrary to its pur-
pose and to our decision in Carter. There is no reason to do
so.
4634          UNITED STATES v. ROMERO-MARTINEZ
                              C.
   [8] Romero-Martinez also argues that the serial number on
the frame of the gun could not qualify for the enhancement
because it was not in compliance with federal law. He asserts
that the serial number violated federal law because Glock “at-
taches a plate containing a number to the frame” rather than
“engrav[ing] or cast[ing] a serial number onto the receiver or
frame itself.” The applicable statutory provision requires that
a manufacturer identify weapons “by means of a serial num-
ber engraved or cast on the receiver or frame of the weapon
. . . .” 18 U.S.C. § 923(i).
   [9] However, as discussed above, the relevant question
under Carter is whether an action has made “accurate infor-
mation less accessible,” not whether a serial number is
required by or compliant with federal law. 421 F.3d at 916.
A serial number is no less accurate if it is cast on the frame
by means of a metal plate rather than directly engraved upon
it. Additionally, the removal of the metal plate certainly
makes the firearm less traceable. Romero-Martinez’s flawed
approach would allow defendants to escape liability merely
because a manufacturer did not perfectly comply with federal
law, even where the non-compliance has no effect on the
accuracy of the information or the traceability of the firearm.
                              V.
   [10] Finally, Romero-Martinez attempts to raise a post-
Booker “unreasonability” challenge to his sentence. This
argument simply restates his previous arguments and uses
them to contend that the resulting sentence was unreasonable.
These underlying arguments were properly rejected for the
reasons given above. To the extent that “reasonableness”
requires independent review, it is plainly reasonable to
impose the enhancement under section 2K2.1(b)(4) where the
gun had not one, but three separately tampered-with serial
numbers.
   AFFIRMED.
