                           In the

United States Court of Appeals
              For the Seventh Circuit

No. 08-2294

U NITED S TATES OF A MERICA,
                                               Plaintiff-Appellee,
                               v.

D AVID O LOFSON,
                                           Defendant-Appellant.


          Appeal from the United States District Court
               for the Eastern District of Wisconsin.
          No. 06 CR 320—Charles N. Clevert, Jr., Judge.



      A RGUED JANUARY 22, 2009—D ECIDED M AY 1, 2009




  Before M ANION and K ANNE, Circuit Judges, and
K ENDALL, District Judge. 
  M ANION, Circuit Judge. David Olofson was indicted for
knowingly transferring a machinegun in violation of 18
U.S.C. § 922(o). A jury convicted Olofson of the charged
offense following a two-day trial, and the district court




  Hon. Virginia M. Kendall, District Judge for the Northern
District of Illinois, is sitting by designation.
2                                               No. 08-2294

sentenced him to thirty months’ imprisonment. Olofson
appeals his conviction. For the following reasons, we
affirm.


                      I. Background
   Robert Kiernicki saw a “for sale” advertisement for a
Colt AR-15 rifle that David Olofson had posted at a gas
station in New Berlin, Wisconsin. Kiernicki called Olofson
at the phone number listed on the ad to inquire about
the weapon. Olofson informed Kiernicki that the adver-
tised gun was no longer available but agreed to order
and assemble another Colt AR-15 for Kiernicki. In the
meantime, Olofson loaned Kiernicki an AR-151 and hun-
dreds of rounds of ammunition on four separate occa-
sions. The selector switch on the borrowed AR-15 had
three positions: one marked “fire,” one marked “safety,”
and one that was unmarked. Olofson and Kiernicki dis-
cussed the unmarked setting on July 13, 2006, which
was the fourth time that Olofson loaned Kiernicki the
weapon. Olofson told Kiernicki that putting the selector
switch in the unmarked position would enable the AR-15
to fire a three-round burst with a single pull of the
trigger, but the gun would then jam.
  While at a shooting range that same day, Kiernicki (for
the first time since using the gun) switched the AR-15 to



1
  Four of the AR-15’s fire control components were parts from
M-16 rifles: the trigger, hammer, disconnector, and selector
switch.
No. 08-2294                                              3

the unmarked position and pulled the trigger; three or
four rounds were discharged before the gun jammed.
Kiernicki fired the weapon in that fashion several times,
and each time it jammed after a short burst of three or
four rounds. Police received a telephone complaint of
automatic gunfire at the shooting range. When officers
arrived at the range, they confiscated the AR-15 from
Kiernicki. Kiernicki told the police that he had borrowed
the gun from Olofson. Several days later, agents from
the Bureau of Alcohol, Tobacco, Firearms and Explosives
(“ATF”) interviewed Olofson while executing a search
warrant at his home. During that conversation, Olofson
acknowledged loaning the AR-15 to Kiernicki.
   On December 5, 2006, a grand jury indicted Olofson
for knowingly transferring a machinegun in violation of
18 U.S.C. § 922(o). Shortly before trial, Olofson filed a
motion to compel the government to disclose evidence
of the ATF’s firearms testing procedures, correspondence
between the ATF and the manufacturer of Olofson’s AR-
15 about the use of M-16 parts in AR-15 rifles, and the
ATF’s registration history of AR-15 rifles that contain M-
16 parts. The district court denied that motion on the
first day of trial after concluding that the information
the defendant was seeking was not exculpatory under
Brady v. Maryland, 373 U.S. 83 (1963).
  At trial, the government asked the district court to
exclude Olofson’s expert witness from the courtroom
during the testimony of its firearms expert. Over Olofson’s
objection, the court granted the government’s request.
The government’s expert testified that he used military-
4                                             No. 08-2294

grade ammunition the first time he test-fired the AR-15
with the selector switch in the unmarked position and that
the gun fired only one round. Later, using civilian-grade
ammunition, he conducted two more test-fires of the
weapon in the unmarked mode. In one of those tests, he
held the trigger down and the gun fired all of its ammuni-
tion (twenty rounds) before stopping. He also emptied
two twenty-round magazines in five- or ten-round bursts
by depressing, holding, and releasing the trigger several
times. The government’s expert stated that such firing
capabilities did not result from a “hammer-follow” mal-
function but rather were intended features of the gun.
  After the close of the evidence, the court used the
definition of a “machinegun” from 26 U.S.C. § 5845(b) to
instruct the jury and chose not to define the word “auto-
matically” from that statute as the defendant had re-
quested. Following deliberation, the jury returned a
guilty verdict. Olofson then moved for a judgment of
acquittal, arguing that the evidence presented at trial
was insufficient to convict him of the charged offense
and that the statutes under which he was prosecuted are
unconstitutionally vague. The district court denied that
motion and sentenced Olofson to thirty months in prison.
Olofson appeals, challenging his conviction on five
grounds.


                      II. Discussion
A. Olofson’s Proposed Jury Instruction
  Title 18 U.S.C. § 922(o)(1) provides that, subject to
exceptions not relevant here, “it shall be unlawful for
No. 08-2294                                                   5

any person to transfer or possess a machinegun.” The
applicable definition 2 of a “machinegun” is
    any weapon which shoots, is designed to shoot, or can be
    readily restored to shoot, automatically more than one shot,
    without manual reloading, by a single function of the
    trigger. The term shall also include the frame or re-
    ceiver of any such weapon, any part designed and
    intended solely and exclusively, or combination of
    parts designed and intended, for use in converting a
    weapon into a machinegun, and any combination
    of parts from which a machinegun can be assembled
    if such parts are in the possession or under the
    control of a person.
26 U.S.C. § 5845(b) (emphasis added). The district court
instructed the jury using the first sentence of § 5845(b)
but did not give any guidance on the meaning of the
word “automatically.” Olofson contends that the court
inaccurately stated the law when it did not instruct the
jury using the definition of “automatically” that derives
from Staples v. United States, 511 U.S. 600, 602 n.1 (1994),
and that we allegedly adopted in United States v.
Fleischli, 305 F.3d 643, 655 (7th Cir. 2002).3 Whether jury


2
  According to 18 U.S.C. § 921(a)(23), “[a]s used in this chap-
ter[,] [t]he term ‘machinegun’ has the meaning given such term
in section 5845(b) of the National Firearms Act (26 U.S.C.
[§] 5845(b)).”
3
  The defendant contends that if that instruction had been
given, the jury could have found him not guilty because a
                                               (continued...)
6                                               No. 08-2294

instructions correctly state the law is a matter we review
de novo. United States v. Thornton, 539 F.3d 741, 745 (7th
Cir. 2008). We will reverse only if the instructions
viewed as a whole misled the jury to the defendant’s
prejudice. Id.
   In Staples, the defendant was convicted of possession
of an unregistered machinegun. 511 U.S. at 603-04. At
trial, the defendant insisted that he did not know that
the weapon was capable of firing automatically (which
is one of the features of a “machinegun” under § 5845(b))
and requested a jury instruction that the government
must prove beyond a reasonable doubt that he knew the
gun could fire in such a manner. Id. The district court
refused to give the defendant’s proposed instruction;
instead, it gave an instruction that discounted the defen-
dant’s need for knowledge of every characteristic of the
weapon that made it subject to regulation. Id. at 604. The
Tenth Circuit affirmed, holding that “the Government
need not prove a defendant’s knowledge of a weapon’s
physical properties to obtain a conviction.” Id. In
reversing, the Supreme Court held that the govern-
ment was required to prove that the defendant knew of
the characteristics of the gun that brought it within
the ambit of the statute. Id. at 619.
  At the beginning of its opinion, the Court quoted the
statutory definition of “machinegun” from § 5845(b) and


3
  (...continued)
malfunction was the reason the weapon stopped firing or,
alternatively, was what caused the gun to fire more than one
round with a single trigger pull.
No. 08-2294                                                    7

stated that “any fully automatic weapon is a ‘firearm’
within the meaning of the Act.” Id. at 602. In a footnote,
the Court then said the following:
    As used here, the terms “automatic” and “fully auto-
    matic” refer to a weapon that fires repeatedly with a
    single pull of the trigger. That is, once its trigger is
    depressed, the weapon will automatically continue to fire
    until its trigger is released or the ammunition is exhausted.
    Such weapons are “machineguns” within the
    meaning of the Act.
Id. at n.1 (emphasis added).
  The narrow holding from Staples is that mens rea was
an element of the crime in question—i.e., that the gov-
ernment had to prove the defendant’s knowledge of the
features of the weapon (including automatic firing cap-
ability) that brought it within the proscriptive purview of
the statute. Id. at 619. The precise definition of “automati-
cally” was not at issue; therefore, the Court’s discussion of
the terms “automatic” and “fully automatic” was immate-
rial to its holding. Indeed, the Court prefaced its explana-
tion of the terms “automatic” and “fully automatic” with
the phrase “[a]s used here.” Thus, rather than interpreting
a statute, the Court simply was providing a glossary
for terms frequently appearing in the opinion. Therefore,
Staples did not establish a requirement for district courts
to instruct juries on the meaning of “automatically” from
§ 5845(b).
  The same is true of our decision in Fleischli. In that case,
the defendant was convicted of two counts of possession
8                                               No. 08-2294

of machineguns in violation of 18 U.S.C. § 922(o)(1).
Fleischli, 305 F.3d at 647. The defendant argued that a
certain weapon was not a machinegun under § 5845(b)
because it did not fire automatically and did not have a
trigger. Id. at 654. Fleischli relied upon the definition of
a semiautomatic rifle from 18 U.S.C. § 921(a)(28) to assert
that a gun does not fire automatically “unless it uses a
portion of the energy of a firing cartridge to extract the
fired cartridge and chamber the next round without a
separate pull of the trigger.” Id. at 655. This court con-
cluded that the gun’s electronic on/off switch that
initiated the firing sequence was a trigger and, having
quoted from footnote one in Staples, stated that if the
gun continued to fire until that switch was turned off
or until the ammunition was exhausted, it was a
machinegun. Id. at 655-56.
  Olofson suggests that Fleischli obliged the district court
to give his proffered instruction. True, in Fleischli we
did borrow terminology from Staples in order to stamp
out the appellant’s “disingenuous argument”; id. at 655;
however, we never purported to be setting forth a com-
prehensive definition of “automatically” from § 5845(b).
Indeed, we described the Staples footnote as merely
“offer[ing] commonsense explanations” of the words
“automatic” and “semiautomatic,” which confirms that
we did not consider that passage to be precedentially
binding. As we explain below, a weapon does not have
to continue to fire until its trigger is released or its am-
munition is exhausted in order to qualify as a
“machinegun” under § 5845(b). Therefore, Olofson’s
reliance on Fleischli for that proposition is misplaced.
No. 08-2294                                                9

  We turn now to address what the word “automatically”
means as it is used in the definition of “machinegun” in
§ 5845(b). “Statutory interpretation begins with the
plain language of the statute.” United States v. Berkos, 543
F.3d 392, 396 (7th Cir. 2008). We assume that the
purpose of the statute is communicated by the ordinary
meaning of the words Congress used; therefore, absent
any clear indication of a contrary purpose, the plain
language is conclusive. Id.
  Again, “[t]he term ‘machinegun’ means any weapon
which shoots, is designed to shoot, or can be readily
restored to shoot, automatically more than one shot,
without manual reloading, by a single function of the
trigger.” 26 U.S.C. § 5845(b). “The most relevant time
for determining a statutory term’s meaning” is the year
of the provision’s enactment. MCI Telecomms. Corp. v. Am.
Tel. & Tel. Co., 512 U.S. 218, 228 (1994) (citing Perrin v.
United States, 444 U.S. 37, 42-45 (1979)). Therefore, we
examine how “automatically” was commonly used and
understood in 1934, the year in which the definition of
“machinegun” became law with the passage of the Na-
tional Firearms Act, Pub. L. 73-474, 48 Stat. 1236. A
leading dictionary from 1934 tells us that “automatically”
is the adverbial form of “automatic.” W EBSTER’S
N EW INTERNATIONAL D ICTIONARY 187 (2d ed. 1934). The
adjectival form of “automatic” is relevantly defined by
that dictionary as “[h]aving a self-acting or self-
regulating mechanism that performs a required act at a
predetermined point in an operation[.]” Id. Another
contemporaneous dictionary similarly describes “auto-
matic” as “[s]elf-acting under conditions fixed for it, going
10                                                 No. 08-2294

of itself.” O XFORD E NGLISH D ICTIONARY 574 (1933).4 Thus
defined, in § 5845(b) the adverb “automatically,” as it
modifies the verb “shoots,” 5 delineates how the dis-
charge of multiple rounds from a weapon occurs: as the
result of a self-acting mechanism. That mechanism is one
that is set in motion by a single function of the trigger
and is accomplished without manual reloading.
   That interpretation clearly forecloses the argument that
a weapon is not a machinegun merely because it stopped
firing due to a malfunction; indeed, the reason a weapon
ceased firing is not a matter with which § 5845(b) is
concerned. Under that interpretation, however, a defen-
dant can still argue that the reason a gun fired more than
one round (with a single pull of the trigger without
manual reloading) was due to a malfunction—i.e., the
additional rounds fired resulted from a mishap rather
than from a regular self-acting mechanism.
  In light of the foregoing interpretation, we conclude
that Olofson’s proffered instruction was not an accurate
statement of the law and that the district court properly
rejected it. Moreover, the district court correctly used
§ 5845(b) to instruct the jury. As used in the statute,


4
   Modern versions of those two dictionaries define “automatic”
in the same terms. W EBSTER ’S T HIRD N EW I NTERNATIONAL
D ICTIONARY 148 (2002); O XFORD E NGLISH D ICTIONARY 805 (2d ed.
1989).
5
  For the sake of efficiency and readability, we use the term
“shoots” as shorthand for “shoots, is designed to shoot, or can
be readily restored to shoot,” unless otherwise indicated.
No. 08-2294                                                11

“automatically” comports with its ordinary modern
meaning, see note 4, that is readily accessible to laypersons
and is in no sense confusing; therefore, the district court
was not required to define that term for the jury. United
States v. Castillo, 406 F.3d 806, 821 (7th Cir. 2005); Miller
v. Neathery, 52 F.3d 634, 638 (7th Cir. 1995).


  B. Sufficiency of the Evidence
  Olofson contends that the evidence presented at trial
was insufficient to sustain his conviction. When a defen-
dant challenges the sufficiency of the evidence, we
view the evidence in the light most favorable to the
government and will reverse the conviction only if no
rational jury could have found the defendant guilty
beyond a reasonable doubt. United States v. Castaldi, 547
F.3d 699, 705 (7th Cir. 2008). In order to convict a person
of violating 18 U.S.C. § 922(o)(1), the government must
prove that 1) the defendant possessed or transferred a
machinegun 2) with knowledge that the weapon had
the characteristics that bring it within the statutory defini-
tion of a machinegun. United States v. McGiffen, 267
F.3d 581, 590 (7th Cir. 2001).
  Regarding the first element, Kiernicki testified that
Olofson loaned him the AR-15 on four occasions, the last
of which was July 13, 2006. An ATF agent also testified
that Olofson admitted loaning the gun to Kiernicki. In
addition, Kiernicki stated that the gun fired three or
four rounds (on several occasions) with one pull of the
trigger. The government’s expert who test-fired the AR-
12                                                No. 08-2294

15 stated that he exhausted a twenty-round magazine
with one continuous depression of the trigger and
emptied two additional twenty-round magazines in five-
or ten-round bursts by intermittently depressing, holding,
and releasing the trigger. He also declared that the
weapon was intended to fire in such fashions and that a
“hammer-follow” malfunction was not the cause. That
evidence was adequate to permit a reasonable jury to
find beyond a reasonable doubt that Olofson transferred
a “machinegun” as defined by § 5845(b). Regarding the
evidence on the knowledge element, Kiernicki said that
Olofson told him “the three-round burst wouldn’t work
and that it would jam up.” Kiernicki understood that
statement to mean that “[t]hree rounds come out of it
when you would pull the trigger” once. That testimony
was sufficient for a reasonable jury to find beyond a
reasonable doubt that the defendant knew that the AR-15,
with a single pull of the trigger and without manual
reloading, could shoot more than one round as the result
of a self-acting mechanism. For these reasons, the defen-
dant’s challenge to the sufficiency of the evidence fails.6


    C. Unconstitutional Vagueness
 Olofson argues that 18 U.S.C. §§ 922(o) and 924(a)(2) are
unconstitutionally vague. We review the constitutionality


6
  The jury heard the testimony of the defendant’s firearms
expert about the AR-15’s supposed malfunctioning and obvi-
ously rejected it; on a sufficiency-of-the-evidence challenge,
we will not second-guess the jury’s credibility determinations.
United States v. Brandt, 546 F.3d 912, 917 (7th Cir. 2008).
No. 08-2294                                               13

of a statute de novo. United States v. Warner, 498 F.3d 666,
697 (7th Cir. 2007). A statute is unconstitutionally vague
if it either “1) does not provide a person of ordinary
intelligence a reasonable opportunity to know what is
prohibited, or 2) fails to provide explicit standards to
prevent arbitrary and discriminatory enforcement by
those enforcing the statute.” United States v. Lim, 444
F.3d 910, 915 (7th Cir. 2006). A vagueness challenge such
as this one that does not implicate First Amendment
freedoms is analyzed as applied to the specific facts of
the case. Id.
  To the extent Olofson contends that the statutes are
fatally vague due to the way “automatically” is used in the
incorporated definition of “machinegun” from § 5845(b),
we disagree. We have already noted that the common
meaning of “automatically” is readily known by lay-
persons and thus a specific instruction defining the term
for the jury was unnecessary. Similarly, a person of ordi-
nary intelligence would have understood the common
meaning of the term—“as the result of a self-acting mecha-
nism”—and thus would have had fair warning of the
relevant features of a weapon that § 5845(b) covers and that
§§ 922(o) and 924(a)(2) regulate. Therefore, we reject
Olofson’s argument that §§ 922(o) and 924(a)(2) are uncon-
stitutionally vague.7




7
  Olofson does not present any cogent argument that §§ 922(o)
and 924(a)(2) lack standards to prevent arbitrary or discrim-
inatory enforcement.
14                                               No. 08-2294

  D.    Exclusion of Olofson’s Firearms Expert from the Court-
       room
  The defendant also argues that the district court improp-
erly granted the government’s request to exclude his
firearms expert (Len Savage) from the courtroom during
the testimony of the government’s firearms expert. Olofson
contends that the presence of his expert during the testi-
mony of the government’s expert was essential to the
presentation of his case.
  Under Federal Rule of Evidence 615, “[a]t the request of
a party the court shall order witnesses excluded so that
they cannot hear the testimony of other witnesses, and
it may make the order of its own motion.” That rule
does not authorize the exclusion of four categories of
persons, including “a person whose presence is shown
by a party to be essential to the presentation of the
party’s cause.” FED. R. E VID. 615(3). As the party asserting
a Rule 615(3) exception, Olofson bore the burden for
showing that the exception applied. Opus 3, Ltd. v. Heritage
Park, Inc., 91 F.3d 625, 628 (4th Cir. 1996); United States
v. Jackson, 60 F.3d 128, 135 (2d Cir. 1995). We review for
an abuse of discretion a district court’s decision about
the essentiality of a witness’s presence under Rule 615(3).
Milicevic v. Fletcher Jones Imports, Ltd., 402 F.3d 912, 916
(9th Cir. 2005); Opus 3, 91 F.3d at 629; Jackson, 60 F.3d
at 135-36.
  At trial, Olofson presented two reasons for opposing the
government’s request to exclude Savage from the court-
room. First, he argued that because Federal Rule of Evi-
dence 703 permits an expert to base his opinion upon facts
No. 08-2294                                                 15

or data made known to him at trial, Savage “should be
allowed to be present to hear” the government expert’s
testimony. However, merely because Rule 703 contem-
plates that an expert may render an opinion based on
facts or data made known at trial does not necessarily
mean that an expert witness is exempt from a Rule 615
sequestration order. The text of Rule 615 plainly does not
provide for such a per se exception; rather, Rule 615(3)
confers discretion upon district courts to determine
whether a given witness (of whatever stripe) is essential.
We agree with the courts of appeals that have addressed
the issue that Rule 703 is not an automatic exemption for
expert witnesses from Rule 615 sequestration. Miller v.
Universal City Studios, Inc., 650 F.2d 1365, 1374 (5th Cir.
1981); Morvant v. Constr. Aggregates Corp., 570 F.2d 626, 630
(6th Cir. 1978); see Opus 3, 91 F.3d at 629. Therefore, the
mere mention of Rule 703 by Olofson was insufficient
to show that a Rule 615(3) exception was warranted.
  Second, Olofson stated that he “would like to have
Mr. Savage present to hear” the government expert’s
testimony on malfunctions so that he could “rebut or add
information” if such testimony was incomplete or incor-
rect. While no precise incantation is required, we doubt
whether those statements advanced the argument that
Savage’s presence was essential under Rule 615(3). Olofson
did not tell the district court (as he tells us on appeal) that
Savage’s presence was of critical import to his highly-
technical defense that the AR-15 malfunctioned. Even
assuming that he did make the argument, Olofson did not
carry his burden of demonstrating essentiality. The defen-
dant stated that Savage should be allowed to hear the
16                                            No. 08-2294

government expert’s testimony so that Savage could “rebut
or add information” to any inaccurate testimony about
malfunctions, but Olofson did not tell the district court
why Savage’s presence was necessary to achieve that end.
Indeed, much of the data and malfunction information
relied upon by the government’s expert was already
known to Savage due to the pre-trial disclosure of the
government expert’s reports, and Savage had the op-
portunity to respond to such materials during the defen-
dant’s case. Regarding any information which was not
included in the reports but may have come into
evidence during the testimony of the government’s
expert, Olofson had ample opportunity on direct examina-
tion for Savage to rebut, add to, or opine on the implica-
tions of such information by asking him to assume its
existence.
  Although it might have been helpful or desirable for
Savage to hear the government expert’s testimony,
Olofson did not show that Savage’s presence was
essential to the presentation of his case. Therefore, the
district court did not abuse its discretion in denying
Savage a sequestration exemption under Rule 615(3).


 E. Denial of Olofson’s Discovery Requests
  Prior to trial and pursuant to Brady, Olofson made a
motion to compel the discovery of evidence he had re-
quested but that the government had not produced. The
defendant sought: 1) documentation of the procedures
used by the ATF in testing the AR-15; 2) correspondence
between the ATF and the manufacturer of the defendant’s
No. 08-2294                                                 17

AR-15 concerning the use of M-16 parts in early AR-15
rifles; 3) information about changes in the ATF’s registry
of AR-15 rifles with M-16 components; and 4) documents
pertaining to the ATF’s refusal to register AR-15 rifles
with M-16 parts. The district court denied the defendant’s
motion on the first day of trial after concluding that
the information sought was not exculpatory. On ap-
peal, Olofson claims that the district court committed
prejudicial error in denying his Brady motion and that he
therefore is entitled to a new trial. We review a district
court’s decision that evidence need not be produced under
Brady for an abuse of discretion. United States v. Dabney,
498 F.3d 455, 459 (7th Cir. 2007).
  Under Brady, the government is constrained to disclose
evidence that is favorable to a defendant and material to
either his guilt or punishment. United States v. Fallon, 348
F.3d 248, 251 (7th Cir. 2003). Favorable evidence
includes both impeachment and exculpatory evidence.
United States v. Baker, 453 F.3d 419, 422 (7th Cir. 2006). Even
when the government has not disclosed such evidence,
“strictly speaking, there is never a real ‘Brady violation’
unless the nondisclosure was so serious that there is a
reasonable probability that the suppressed evidence
would have produced a different verdict.” Strickler v.
Greene, 527 U.S. 263, 281 (1999). “We have described this
inquiry as ‘materiality,’ and stated that the demonstra-
tion of materiality is the key to obtaining a new trial
where a defendant alleges a Brady violation.” Baker, 453
F.3d at 422. Thus there are three parts to a Brady viola-
tion: 1) the disputed evidence must be favorable to the
defendant, either because it is exculpatory or im-
18                                               No. 08-2294

peaching; 2) that evidence must have been suppressed by
the government, either willfully or inadvertently; and 3)
prejudice must have occurred. Strickler, 527 U.S. at 281-82.
  Regarding the first non-disclosed item—the ATF’s
internal procedures for test-firing AR-15 rifles—Olofson
says he wanted that information because “[f]ailure to
follow those procedures by changing the type of am-
munition in the second test could demonstrate that the
tests had been manipulated to arrive at a reversal of the
results of the first test.” We do not see how that informa-
tion could have exculpated Olofson; section 5845(b) does
not require compliance with ATF test-fire procedures in
order for a weapon to qualify as a machinegun, nor
must the weapon fire any particular grade of ammuni-
tion or in the prohibited fashion during the first test-fire.
Assuming that such evidence might have had some
impeachment value, there was no Brady violation because
the government’s expert was otherwise sufficiently im-
peached. United States v. Ervin, 540 F.3d 623, 632 (7th Cir.
2008) (“Brady does not extend to ‘evidence that impeaches
an already thoroughly impeached witness.’ ” (quoting
United States v. Kozinski, 16 F.3d 795, 819 (7th Cir. 1994))).
Specifically, Olofson questioned the government’s expert
at length about ATF test-fire procedures and the types of
ammunition used in the tests. In addition, the govern-
ment’s expert admitted that the gun fired automatically
more than one round with a single function of the trigger
without manual reloading in the second test with civilian-
grade rounds, but jammed in the first test with military-
grade rounds. Even if the second test was inconsistent
with ATF procedures, that fact would not undermine
No. 08-2294                                                  19

confidence in the outcome of the trial. Kyles v. Whitney, 514
U.S. 419, 434 (1995). Therefore, the district court did not
abuse its discretion in denying the defendant’s motion
to compel the production of that evidence.
  With respect to his request for the ATF’s correspondence
with the manufacturer of his AR-15 concerning the use
of M-16 parts in early AR-15 rifles, the defendant con-
tends that evidence was exculpatory because it was
relevant to his knowledge of whether or not his AR-15
was a machinegun. The district court denied Olofson’s
request on the first day of trial. At the sentencing hearing,
the court revisited the issue; the court inspected a docu-
ment in camera, stated that it was not exculpatory, and
placed it under seal. We subsequently ordered that docu-
ment to be unsealed. That evidence is a 1983 letter from
the ATF to the manufacturer of the AR-15 in which the
ATF advised the company that the installation of certain
M-16 parts in AR-15 receivers may permit the weapon
to fire automatically even though an automatic sear is not
present. We agree with the district court that the docu-
ment is not exculpatory: it has no bearing on Olofson’s
knowledge of whether his AR-15 was a machinegun.8 The


8
  The government’s theory of the case was that the AR-15
functioned as a machinegun, thus implicating the first sentence
of § 5845(b)’s definition of the term. As discussed earlier, the
district court instructed the jury using only that part of
§ 5845(b), and sufficient evidence of Olofson’s knowledge of
the AR-15’s firing capacity was presented to convict him. Had
the government attempted to prove that a part or combination
                                                  (continued...)
20                                              No. 08-2294

letter has no impeachment value either. Therefore, the
district court did not abuse its discretion in refusing to
order the production of that evidence.
  Lastly, Olofson argues that any documents relating to
the ATF’s change in registry or refusal to register AR-15
rifles with M-16 components were exculpatory because
they could have been used to refute the government
expert’s testimony that the M-16 parts in Olofson’s AR-15
made it a machinegun. But the government’s expert did
not testify that the AR-15 was a machinegun merely
because it had M-16 parts; rather, the expert stated that
the AR-15 fired the way it did due in part to the M-16
components. Regardless, like the district court, we do not
see how the ATF’s opinions or positions regarding the
presence of M-16 parts in AR-15 rifles are the least bit
germane to Olofson’s conviction for knowingly transferring
a machinegun. The district court did not abuse its dis-
cretion in denying Olofson’s motion to compel the gov-
ernment to produce that evidence.


                      III. Conclusion
  In sum, the defendant’s proffered jury instruction was
not a correct statement of the law, and the district court



8
  (...continued)
of parts in the AR-15 made it a machinegun under the second
sentence of § 5845(b), then perhaps evidence about the manu-
facturer’s installation of M-16 parts in AR-15s would have
been relevant to the defendant’s knowledge of those parts in
the weapon.
No. 08-2294                                              21

properly rejected it. Furthermore, the evidence presented
at trial was sufficient to sustain Olofson’s conviction, and
18 U.S.C. §§ 922(o) and 924(a)(2) are not unconstitutionally
vague as applied to the facts of this case. In addition, the
district court did not abuse its discretion in either ex-
cluding the defendant’s firearms expert from the court-
room during the government expert’s testimony or in
denying Olofson’s motion to compel the production of
evidence he had requested from the government. Accord-
ingly, we A FFIRM Olofson’s conviction.




                           5-1-09
