222 F.3d 349 (7th Cir. 2000)
UNITED STATES OF AMERICA, Plaintiff-Appellee,v.WILLIE C. JONES, Defendant-Appellant.
No. 00-1199
In the  United States Court of Appeals  For the Seventh Circuit
Argued June 13, 2000Decided July 21, 2000

Appeal from the United States District Court  for the Southern District of Illinois.  No. 99 CR 40053--William D. Stiehl, Judge.
Before COFFEY, RIPPLE, and KANNE, Circuit Judges.
RIPPLE, Circuit Judge.


1
Attempting to break up a  domestic argument, police officer Ron Almaroad  helped Willie Jones move his property from the  front lawn of his ex-wife's apartment building to  a nearby residence. Among other items, Mr. Jones  placed a .30 caliber semi-automatic rifle in the  backseat of the police car. Despite Mr. Jones'  assertion that the rifle was a "BB gun," Officer  Almaroad arrested him because the officer knew  that he was a felon and, therefore, was  prohibited by law from possessing the firearm.


2
A federal grand jury then indicted Mr. Jones for  possession of a firearm by a felon, in violation  of 18 U.S.C. sec. 922(g)(1). At trial, Mr. Jones  did not testify, but he sought to establish  through cross-examination and argument that he  thought the rifle was a BB gun and, therefore,  that he did not knowingly possess a firearm. See  18 U.S.C. sec.sec. 922(g)(1), 924(a)(2). To  undermine this defense, the prosecution offered  as evidence, a .30 caliber cartridge and standard  air rifle ammunition--two BBs and a .177 caliber  pellet. The ammunition, none of which was  recovered from Mr. Jones, was offered over  objection for demonstrative purposes. A jury  found Mr. Jones guilty, and the district court  then sentenced him to 200 months' imprisonment.  He appeals, arguing that the district court erred  both when it admitted the ammunition and when it  denied his motion for judgment of acquittal. For  the reasons set forth in the following opinion,  we affirm the judgment of the district court.


3
* BACKGROUND


4
At trial, Mr. Jones stipulated to his prior  felony conviction and did not dispute that he  possessed the firearm or that it previously had  moved in or affected interstate commerce. Officer  Almaroad testified that, on July 15, 1998, he  responded to a report of a domestic disturbance.  Upon arriving at the residence, Officer Almaroad  observed that police officers were already on the  scene and had separated Mr. Jones from Carolyn  Doggin, his ex-wife. Once Officer Almaroad  ascertained that no offense had occurred in  connection with the domestic dispute, he offered  to drive Mr. Jones away from the area in order to  avoid any further conflict. Mr. Jones agreed and  said that he would like to take some personal  items. Officer Almaroad helped Mr. Jones load a  typewriter and a television into his squad car.  After Officer Almaroad seated himself in the  driver's seat, he looked in the rearview mirror  and observed Mr. Jones place a rifle in the  backseat. Mr. Jones then sat in the front  passenger's seat. Officer Almaroad inquired as to  the item that Mr. Jones had placed in the  backseat. Mr. Jones replied that it was a BB gun.


5
The prosecution offered the rifle into evidence,  allowing the jurors to handle the firearm, to  feel the weight of the gun and to observe the  diameter of the rifle's bore. The prosecution  also offered as demonstrative evidence a .30  caliber cartridge, and standard air rifle  ammunition--two BBs and a .177 caliber pellet--to  show the difference between the bore of a BB gun  and that of a .30 caliber rifle. The court  admitted the ammunition evidence over objection  from Mr. Jones, who sought to exclude it on the  theory that the police had not recovered it from  him or found it with the gun. Additionally,  Officer Almaroad and Illinois State Police Crime  Lab Technician Robert Dunbar testified that, upon  viewing the weapon, they immediately knew that  the rifle was not a BB gun. Mr. Jones never  requested a cautionary instruction concerning the  ammunition, and the court did not give one in its  final charge to the jury.

II
DISCUSSION
A.  Admissibility of the Ammunition

6
Mr. Jones first argues that the district court  should have excluded the ammunition evidence as  irrelevant. He contends that it was not found in  his possession and so was not probative of  whether he knew the instrument he possessed was a  firearm. Because Mr. Jones objected to the  ammunition's relevancy at trial, we review the  district court's decision to admit that evidence  for an abuse of discretion. See United States v.  Montani, 204 F.3d 761, 765 (7th Cir. 2000).


7
Relevant evidence is defined as evidence "having  any tendency to make the existence of any fact  that is of consequence to the determination of  the action more probable or less probable than it  would be without the evidence." Fed. R. Evid.  401; United States v. Griffin, 194 F.3d 808, 821  n.6 (7th Cir. 1999), cert. denied, 120 S. Ct.  1546 (2000). At trial, Mr. Jones' sole defense--  one presented exclusively through cross-  examination and argument by counsel--was that he  thought that the instrument he possessed was a BB  gun. The prosecution's ammunition evidence  demonstrated the size differences between .30  caliber ammunition and standard BB gun ammunition  and between the BB gun ammunition and the bore of  Mr. Jones' rifle. This evidence rendered less  probable Mr. Jones' contention that he thought  his rifle was a BB gun; therefore, the ammunition  evidence was relevant. Because relevant evidence  is admissible under Federal Rule of Evidence 402,  the district court did not abuse its discretion  in admitting the ammunition. See Griffin, 194  F.3d at 821 n.7.


8
Mr. Jones also contends that admission of the  ammunition was "highly prejudicial." We note,  however, that despite two opportunities to do so,  Mr. Jones did not request that the jury be  cautioned that the ammunition was admitted solely  for demonstrative purposes. We cannot say that  the district court erred in concluding that the  probative value of the evidence was not  substantially outweighed by the danger of unfair  prejudice. See Fed. R. Evid. 403.

B.  Motion for Judgment of Acquittal

9
Mr. Jones next argues that the district court  erred in denying his motion for judgment of  acquittal. We review a district court's denial of  a motion for acquittal de novo. See United States  v. Blassingame, 197 F.3d 271, 284 (7th Cir.  1999), cert. denied, 120 S. Ct. 2024 (2000). Such  motions should be granted only where "the evidence is insufficient to sustain a  conviction." Fed. R. Crim. P. 29(a). In  considering the sufficiency of the evidence, we  review it in the light most favorable to the  prosecution, see United States v. Hach, 162 F.3d  937, 942 (7th Cir. 1998), cert. denied, 119 S.  Ct. 1586 (1999), and as long as any rational jury  could have returned a guilty verdict, the verdict  must stand. See Blassingame, 197 F.3d at 284.


10
To prove that a defendant is guilty of  possession of a firearm by a felon, the  Government must establish that: (1) the defendant  knowingly possessed a firearm; (2) he previously  had been convicted of a crime punishable by  imprisonment for a term exceeding one year; and  (3) the possession of the firearm was in or  affecting interstate commerce. See 18 U.S.C.  sec.sec. 922(g)(1), 924(a)(2). See also United  States v. Johnson, 127 F.3d 625, 629 (7th Cir.  1997). In this case, Mr. Jones does not dispute  the sufficiency of the prosecution's evidence as  to elements two and three; he argues only that  the prosecution failed to present sufficient  evidence that he knew that the object he  possessed was a firearm. To prove that a  defendant "knowingly possessed a firearm," the  Government must establish that the defendant  consciously possessed what he knew to be a  firearm. See United States v. Deleveaux, 205 F.3d  1292, 1298 (11th Cir. 2000), cert. denied, ___ S.  Ct. ___ (2000); United States v. Frazier-El, 204  F.3d 553, 561 (4th Cir. 2000); United States v.  Reed, 114 F.3d 1053, 1056 (10th Cir. 1997). The  Government argues that it presented sufficient  evidence, i.e., the rifle, the demonstrative  ammunition, and the testimony from two police  witnesses, to prove that Mr. Jones knowingly  possessed the rifle.


11
We first note that the rifle alone provided the  jury with a sufficient basis to reasonably  conclude that Mr. Jones knew that he possessed a  "firearm" and not a BB gun. Due to a lack of sec.  922(g)(1) cases on point, we are guided by  sufficiency-of-the-evidence cases discussing a  similar knowledge requirement under the National  Firearms Act, 26 U.S.C. sec.sec. 5801-72, in  evaluating the probative value of the rifle as  evidence of Mr. Jones' knowledge. We conclude  that the rifle was sufficient evidence for a jury  to find that Mr. Jones knew that he possessed a  firearm. Under sec. 5861(d), it is unlawful to  possess an unregistered "firearm," as that term  is defined in the Act. See 26 U.S.C. sec.  5861(d). Included within the definition of  "firearm" is a shotgun with an overall length of  less than twenty-six inches or a barrel length of  less than eighteen inches. See 26 U.S.C. sec.  5845. To obtain a conviction under the National  Firearms Act, the government must prove that the  defendant knew of the particular characteristics  that brought his weapon within the scope of the  Act. See Staples v. United States, 511 U.S. 600,  619 (1994); United States v. Edwards, 90 F.3d  199, 204-05 (7th Cir. 1996) (holding that the  government must prove that the defendant knew  that the barrel of his shotgun was less than  eighteen inches).


12
In prosecutions under the National Firearms Act,  courts have held that evidence a defendant  observed and handled his "sawed-off shotgun" is  sufficient for a jury reasonably to infer that  the defendant knew that the weapon was shorter  than twenty-six inches overall or had a barrel  length of less than eighteen inches.1 Here, the  prosecution presented evidence from which a  rational jury could infer that Mr. Jones  possessed what he knew to be a firearm. The  jurors inspected the rifle at trial. Based on the  rifle's obvious characteristics--the diameter of  the rifle's bore, the rifle's weight, and its  general appearance--the jury could infer that Mr.  Jones knew that the instrument he possessed was a  firearm, not a BB gun. The ammunition and the  testimony of Officer Almaroad and Mr. Dunbar adds  to the sufficiency of the prosecution's evidence,  providing further support for the jury's  conclusion that Mr. Jones knew that he possessed  a firearm. Accordingly, we conclude that a  rational jury could have determined that Mr.  Jones knowingly possessed a firearm.

Conclusion

13
Because the ammunition evidence was probative of  Mr. Jones' knowledge that the instrument he  possessed was a firearm, the district court did  not err in admitting the ammunition. As well, the  government presented sufficient evidence to  support the jury's determination that Mr. Jones  knowingly possessed a firearm. Consequently, the  district court properly denied Mr. Jones' motion  for judgment of acquittal. Accordingly, the  judgment of the district court is affirmed.

AFFIRMED


Note:


1
 See United States v. Gergen, 172 F.3d 719, 725  (9th Cir. 1999) (reasoning that "[e]xternally  visible characteristics weigh heavily as to . . .  knowledge of the shotgun's dangerous  characteristics"); United States v. Jackson, 124  F.3d 607, 614 (4th Cir. 1997) (concluding that  the defendant's knowledge of the proscribed  nature of the firearm could be inferred from his  possession of the weapon because it was "an  obvious 8 inches shorter than that permitted  under the statute"); United States v. Moore, 97  F.3d 561, 564 (D.C. Cir. 1996) (concluding that  the jury could have reasonably inferred that the  defendant knew the rifle was shorter than 16  inches by observing the 13-1/16 inch weapon);  United States v. Foster, 19 F.3d 1452, 1454 (D.C.  Cir. 1994) (concluding that the readily apparent  barrel length and general appearance of the  sawed-off rifle were sufficient to allow a jury  to conclude that the defendant had the requisite  knowledge); see also Edwards, 90 F.3d at 20  (noting that the fact that the shotgun's length  is externally obvious is a means of proving  knowledge). Similarly, in United States v.  Thompson, 82 F.3d 849, 854 (9th Cir. 1996), the  Ninth Circuit held that the prosecution presented  sufficient evidence to prove that the defendant  knew that his unregistered "fake suppressor"--an  aesthetic gun accessory designed to look like a  silencer--had been modified to work as a real  silencer in violation of the National Firearms  Act. The court, reasoning that the defendant's  "knowledge can be inferred from . . . any  external indications signaling the nature of the  weapon," found the evidence sufficient primarily  due to a government expert's testimony that upon  viewing the modified suppressor "anyone could  notice" that holes had been drilled in the device  to transform it into a functioning silencer. Id.  (quoting Staples, 511 U.S. at 615 n.11).


