VAN ANTWERPEN, Circuit Judge.

David Wayne Hull appeals from the judgment of conviction entered by the District Court after he was found guilty by a jury on 7 of 10 counts related to explosives, firearms, and witness tampering. We will vacate Hull's conviction as to Count 7, and affirm the judgment of conviction as to all remaining counts.

I.

David Wayne Hull, the admitted Imperial Wizard of the splinter group White Knights of the Ku Klux Klan, was arrested on February 13, 2003. A search warrant was executed by law enforcement on his home. Agents found loaded handguns, a rocket tube, military-style weapons, ammunition, a silencer and accompanying instructions for manufacture, diagrams and instructions for making pipe bombs and booby-traps, explosives components, and, outside the home, cars damaged by explosions but still containing parts of pipe bombs. Hull did not have licenses or registrations for any of the weapons or explosives, or the silencer.

The FBI had had Hull under surveillance and investigation for several years, utilizing a government informant to infiltrate and observe the KKK. This informant met Hull and other members of the KKK at various gatherings and privately at Hull's house. The informant watched and participated in the detonation of several pipe bombs and other explosives, and the testing of silencers. The informant also discussed the making of pipe bombs with Hull, and repeatedly requested that Hull construct pipe bombs for him. At some point, Hull apparently deduced the informant was just that, and allegedly took steps to provide him with only bomb components (minus the fuse) instead of a completed pipe bomb. The informant also cooperated with the FBI to record conversations with Hull, beginning in September 2002.

A District Judge from the Eastern District of Pennsylvania approved a wiretap interception order on January 13, 2003, for various suspects' phones, including Hull's home and cell phones. In the supporting wiretap affidavit, agents promised to "minimize" the interceptions by screening out: calls under two minutes; calls not involving Hull or any other named interceptee; and conversations "non-criminal in nature." The agents reserved the right to "spot-check" any of these calls to "ensure that the conversations have not turned to criminal matters." In practice, this procedure involved initial monitoring for identity and subject verification; one minute without monitoring if the call fell into an above category; then two minutes of active monitoring for "spot-checking"; and so forth until the call was completed. Several of the resulting intercepts were later used in Hull's trial.

Hull was eventually indicted by a federal grand jury, which indictment was followed by a ten-count superseding indictment. The superseding indictment charged Hull with: Counts 1, 2, 3, and 4, possession of unregistered firearms (pipe bombs and a silencer) on various dates; Count 5, transfer of a firearm (pipe bomb); Count 6, manufacture of a firearm (pipe bomb); Counts 7 and 8, teaching or demonstrating, and distributing information regarding, the making and use of a pipe bomb with the intent that the teaching or information be used for a "Federal crime of violence" ("unlawful possession of a pipe bomb") on two dates; Count 9, possession of a firearm in interstate commerce by a felon; and Count 10, attempting to influence the testimony of a witness.

Hull pleaded not guilty and moved to have the wiretap interceptions suppressed. The District Court denied the motion on May 7, 2004, and the case was tried to a jury in the Western District of Pennsylvania. Over the course of several weeks, the jury heard testimony from various FBI and law enforcement agents, technical experts, and several informants and cooperating witnesses. One of Hull's girlfriends, Deborah Rusch, testified that she had helped Hull by using her legal secretary position and skills to format articles for publication in a KKK newspaper. The articles dealt with topics including the manufacture of propane tank explosives and pipe bombs; several were attributed to an author identified as the "Unknown Terrorist." Rusch had also had conversations with Hull about explosives. Rusch later received several letters from Hull while he was in prison, and turned these letters over to the FBI. The letters asked her to "remember" several conversations; to say that they were merely "casually dat[ing]" instead of calling herself his girlfriend; reminded her of things she "knew"; listed things she "must tell . . . to the jury"; and, most critically, to tell the jury that she did not believe Hull wrote the "Unknown Terrorist" articles. She was then instructed to burn one of the letters. On the stand, Rusch testified instead that she did not recall ever speaking with a specific FBI agent, as alleged in the letters, and that she did believe Hull to be the Unknown Terrorist, as most, but not all, of the articles matched his writing style.

Hull took the stand in his own defense, and testified that neither he nor the White Knights had ever espoused violence, or had intended to hurt anyone. He denied being the "Unknown Terrorist," or that he had ever demonstrated how to make a pipe bomb to anyone or participated in detonating any pipe bombs. All the firearms and explosives components, he alleged, were for legitimate purposes. He claimed that he knew all along that the informant was helping law enforcement, and therefore purposefully refused to give him an assembled bomb.

At the close of the trial, the District Court instructed the jury. In particular, the District Court refused to include a proposed instruction from Hull that in order to be found guilty of "transferr[ing]" a firearm, he had to know and intend that the bomb, unassembled and without a fuse, constitute a firearm. The District Court did instruct the jury that mere possession of a bomb could qualify as a "Federal crime of violence," after expressing deep doubts over the issue and noting that the court had not "made up my mind on this."

On May 28, 2004, the jury returned verdicts of not guilty on 3 of the 10 counts (possession of a pipe bomb on 2 of 3 relevant dates, and distribution of information related to a pipe bomb on one date). The jury found Hull guilty of the remaining 7 counts. On March 21, 2005, the District Court sentenced Hull to 144 months imprisonment for the distribution of information related to a pipe bomb (Count 7), to run concurrently with sentences of 120 months imprisonment for each of the remaining six counts of conviction. Hull now appeals his conviction on myriad grounds.

II.

Hull raises five challenges to his conviction, one of which we find meritorious and thus will address first in detail. Hull alleges that: (1) mere "possession" of a pipe bomb, as charged in the indictment, does not qualify as a "Federal crime of violence" under 18 U.S.C. § 842(p)(2)(A); (2) the evidence was insufficient to prove the witness tampering change; (3) the wiretaps should have been suppressed due to the Government's failure to properly "minimize" interceptions; (4) for the purpose of making, possessing, or transferring a firearm, Hull could not be convicted because he did not intend that a pipe bomb, unassembled, be assembled into a firearm; and (5) 18 U.S.C. § 922(g)(1), felon in possession of a firearm, is unconstitutional. We have rejected this last contention outright, and will not give it further consideration here. United States v. Singletary, 268 F.3d 196 (3d Cir. 2001).

III.

Hull's first argument presents a matter of first impression in this Court, and to our knowledge, in any court of appeals. Hull was convicted, at Count 7, of violating 18 U.S.C. § 842(p)(2)(A):

"(p) Distribution of information relating to explosives, destructive devices, and weapons of mass destruction.

(1) Definitions. In this subsection —

(A) the term `destructive device' has the same meaning as in section 921(a)(4);

(B) the term `explosive' has the same meaning as in section 844(j); and

(C) the term `weapon of mass destruction' has the same meaning as in section 2332a(c)(2).

(2) Prohibition. It shall be unlawful for any person —

(A) to teach or demonstrate the making or use of an explosive, a destructive device, or a weapon of mass destruction, or to distribute by any means information pertaining to, in whole or in part, the manufacture or use of an explosive, destructive device, or weapon of mass destruction, with the intent that the teaching, demonstration, or information be used for, or in furtherance of, an activity that constitutes a Federal crime of violence;" (emphasis added)

The superseding indictment charged that the "Federal crime of violence" at issue was solely the "unlawful possession of a pipe bomb," on or about November 19, 2002. As we will set out below, "crime of violence" is not defined in the statute.

The District Court instructed the jury that:

"[P]ossession of an unregistered pipe bomb is a federal crime of violence. . . . The government does not have to prove defendant intended the recipient of the information to blow up someplace or blow up somebody. They need only prove that the defendant intended the recipient of this information to make and thereafter possess the pipe bomb."

Hull alleges that simple possession of a pipe bomb, as opposed to the use or detonation of a pipe bomb, cannot qualify as a "Federal crime of violence" under § 842(p)(2)(A), and that his conviction at Count 7 must be vacated. We exercise plenary review over questions of law, such as whether a crime is a crime of violence, United States v. Luster, 305 F.3d 199, 200 (3d Cir. 2002). We will vacate the conviction for Count 7.

We note first the regrettable fact that we do not have the benefit of any analysis or ruling by the District Court on this issue. The District Court initially expressed its "concern" to the parties during trial that "if the mere possession satisfied the crime of violence element, why even put that element into it? Transferring it implies the other person is going to possess it. . . . [that is,] [t]he teaching charge, not the transfer, the teaching charge." App. vol. IV. 1109. Both Hull and the Government submitted memoranda on the point, and while later in the trial, the District Court returned to the issue again, expressing doubt on the Government's theory of the charge, it did not analyze the issue on the record:

"I read your briefs about this, whether or not mere possession alone constitutes a crime of violence. I think it is a very close question. I haven't made up my mind on this. Probably what I will do, though, is I might submit it to the jury as proffered by the government, and then in post-verdict motions, if they find the guy not guilty, then it's moot. If they find him guilty, then as a matter of law, I can rule whether or not to take out the verdict. And then if it goes to the Court of Appeals, at least we'll have a verdict. If I'm wrong, we'll have to do it again." App. vol. IV. 1348.

The District Court then gave the requested jury instruction we have set forth above, without further discussion.

With regard to 18 U.S.C. § 842(p)(2)(A), we are treading on fairly undisturbed ground. Section 842(p) was added to the criminal code in 1999, see P.L. 106-54 § 2(a), 113 Stat. 398 (Aug. 17, 1999), and as yet has been applied only sparingly across the country.

Unfortunately, as we noted above § 842(p) does not define "Federal crime of violence." Accordingly, the Supreme Court recently instructed courts to look at 18 U.S.C. § 16's definition of "crime of violence" for the purposes of 18 U.S.C. § 842(p). Leocal v. Ashcroft, 543 U.S. 1, 7 n. 4, 125 S.Ct. 377, 160 L.Ed.2d 271 (2004) ("a number of statutes criminalize conduct that has as an element the commission of a crime of violence under § 16. See, e.g., 18 U.S.C. § 842(p)"). Leocal, which examined in detail § 16's usage of the term, therefore controls our analysis under § 842. 18 U.S.C. § 16 defines "crime of violence" as follows:

"(a) an offense that has as an element the use, attempted use, or threatened use of physical force against the person or property of another, or

(b) any other offense that is a felony and that, by its nature, involves a substantial risk that physical force against the person or property of another may be used in the course of committing the offense." (emphases added)

The Supreme Court in Leocal considered whether a conviction for a state DUI offense that did not require proof of a mental state nonetheless qualified as a crime of violence under § 16. The Court concluded that it did not fit either § 16(a) or (b). Under § 16(a), the Court held that "use" requires the "active employment" of force, and therefore a degree of intent higher than negligence. Leocal, 543 U.S. at 9, 125 S.Ct. 377. Nor did the DUI conviction qualify under § 16(b), which "covers offenses that naturally involve a person acting in disregard of the risk that physical force might be used against another in committing the offense." Leocal, 543 U.S. at 10, 125 S.Ct. 377 (emphasis added). "Thus, § 16(b) plainly does not encompass all offenses which create a `substantial risk' that injury will result from a person's conduct. The `substantial risk' in § 16(b) relates to the use of force, not to the possible effect of a person's conduct." Id. at 10 n. 7, 125 S.Ct. 377.

Here the Government does not allege that possession of a pipe bomb involves the actual use of physical force, only that it involves a substantial risk of use of physical force against another. In light of this and Leocal's holding, we therefore confine our analysis to 18 U.S.C. § 16(b).

Leocal dictates a "categorical" approach to determining whether a crime is a crime of violence. Leocal, 543 U.S. at 8, 125 S.Ct. 377; see also Oyebanji v. Gonzales, 418 F.3d 260, 262 (3d Cir. 2005). "This . . . requires us to look to the elements and nature of the offense of conviction, rather than to the particular facts relating to petitioner's crime." Leocal, 543 U.S. at 8, 125 S.Ct. 377. Our task, then, is to determine whether simply "possessing" a pipe bomb is an "offense that naturally involve[s] a person acting in disregard of the risk that physical force might be used against another in committing the offense." Leocal, 543 U.S. at 10, 125 S.Ct. 377. We hold that it is not.

The Government's argument in favor of the District Court's charge is this: Because there are no "legitimate" uses for a pipe bomb, and because they are such dangerous items, mere possession of a pipe bomb involves the "substantial risk of physical force." Were that the complete test, we might agree. However, the Government ignores the remainder of § 16(b): "may be used in the course of committing the offense," (emphasis added). The Government's argument fails to acknowledge that the Supreme Court in Leocal repeatedly emphasized the importance of the requirement that the force be used in committing the offense, and here the offense is but one of possession. "The risk that an accident may occur when an individual drives while intoxicated is simply not the same thing as the risk that the individual may `use' physical force against another in committing the DUI offense." Leocal, 543 U.S. at 10 n. 7, 125 S.Ct. 377. This element of § 16(b) is perhaps the most important. The Leocal Court rejected, as dissimilar and insufficient, the definition and interpretation of U.S.S.G. § 4B1.2(a)(2)'s definition of "crime of violence," which required only "conduct which presents a serious potential risk of physical injury to another." Leocal, 543 U.S. at 10 n. 7, 125 S.Ct. 377. This latter definition, by contrast, might have covered the possession of a pipe bomb.

The danger from a pipe bomb comes not from the offense of possession, but from the added factor of use of the pipe bomb. See Leocal, 543 U.S. at 9, 125 S.Ct. 377 ("`use' requires active employment") (citing Bailey v. United States, 516 U.S. 137, 143, 116 S.Ct. 501, 133 L.Ed.2d 472 (1995) (substantive holding superseded by statute)); Bailey, 516 U.S. at 144, 116 S.Ct. 501 ("use . . . requires more than a showing of mere possession"). To commit the offense of possession, Hull merely had to exercise control or dominion over the pipe bomb. There is no risk that physical force might be used against another to commit the offense of possession, regardless of whether pipe bombs have a legitimate purpose or not. Cf. United States v. Bowers, 432 F.3d 518, 519 (3d Cir. 2005) ("[A] felon in possession has committed a crime of violence only if the nature of that offense is such that there is a `substantial risk' that he will use `physical force' against another `in the course of' his possession of the weapon.") (emphasis added). In contrast, had Hull been charged in the indictment with using a pipe bomb, then commission of such an offense would "involve a substantial risk that physical force against the person or property of another may be used in the course of committing" that offense. 18 U.S.C. § 16(b). Use of a pipe bomb is the type of "violent, active crime" the Supreme Court found constituted a crime of violence under § 16. Leocal, 543 U.S. at 11, 125 S.Ct. 377 (emphasis added). Possession is simply not such an "active" crime; "A crime that increases the likelihood of a crime of violence need not itself be a crime of violence." United States v. Lane, 252 F.3d 905, 907 (7th Cir. 2001), quoted with approval in Bowers, 432 F.3d at 522.

The Government's theory that a pipe bomb might "go off" at any moment and is therefore inherently, and unredeemably, dangerous, is further foreclosed by our recent decision in Tran v. Gonzales, 414 F.3d 464 (3d Cir. 2005). Tran addressed whether "reckless burning or exploding" constituted a crime of violence under § 16, and concluded that it did not. We held that "§ 16(b) crimes are those raising a substantial risk that the actor will intentionally use force in the furtherance of the offense." Id., 414 F.3d at 471 (emphasis in original). We reasoned that:

"This element [recklessly endangering the property of another], on its face, involves a substantial risk of causing injury to the property of another. But it does not involve a substantial risk of using force against the property of another. The substantial risk involved in the Pennsylvania statute is the risk that the fire started by the offender will spread and damage the property of another. This risk cannot be said to involve the intentional use of force, as required by [United States v.] Parson [, 955 F.2d 858 (3d Cir. 1992)]. The statute does not contemplate a risk that the reckless-burning offender will step in and commit an intentional act of violence. . . ."

Id. at 472-73 (emphasis in original). Similarly here, mere possession of a pipe bomb holds no risk of the intentional use of force. Even if, as the Government posited at argument, a pipe bomb can unexpectedly explode (and the possessor has this knowledge) during even the most passive constructive possessions, such an explosion would not have been the result of any intentional use of force. Possessing a pipe bomb does not necessarily include a substantial risk that the possessor might step in and intentionally detonate the device, i.e., use force within the meaning of § 16.

The Government points us to several other statutes under which courts have found the mere possession of a "firearm" to constitute a crime of violence. We do not find these statutes or case law persuasive with respect to the case at hand. The Government relies most heavily on a Fifth Circuit case, United States v. Jennings, 195 F.3d 795 (5th Cir. 1999), interpreting 18 U.S.C. § 924(c), which defines "crime of violence" in the same language as § 16. The Jennings court held that possession of a pipe bomb satisfied that definition in the context of the possession of a firearm in relation to a crime of violence. First, Jennings is in no way binding on this Court. Second, we disagree with the analysis of the Jennings court because it conflates "use" with "possession," which conflation the Supreme Court took the opportunity to explicitly forbid in its later opinion in Leocal. See, e.g., Jennings, 195 F.3d at 798 ("We hold that possession of an unregistered pipe bomb, by its very nature, creates a substantial risk of violence. . . . In fact, we cannot conceive of any non-violent or lawful uses for a pipe bomb.") (emphases added).

As discussed, the relevant inquiry is not whether possession makes it more likely that a violent crime will be committed, but instead whether there is a risk that in committing the offense of possession, force will be used. See Lane, 252 F.3d at 907.

The remainder of the Government's analogies are similarly inapposite. The Government suggests that we look to cases interpreting U.S.S.G. § 4B1.2 for guidance. Here we are troubled by the Government's lack of candor. Unlike any of the previous definitions of "crime of violence" quoted by the Government, § 4B 1.2(a) (which the Government explicitly does not quote or reference) defines a crime of violence as one that:

"(1) has as an element the use, attempted use, or threatened use of physical force against the person of another, or

(2) is burglary of a dwelling, arson, or extortion, involves use of explosives, or otherwise involves conduct that presents a serious potential risk of physical injury to another." (emphasis added)

Guidelines § 4B1.2 is inapposite to this case for at least two reasons. First, Leocal explicitly rejected using § 4B1.2 to interpret § 16 (and by extension, § 842(p)). Leocal, 543 U.S. at 10 n. 7, 125 S.Ct. 377. Second, § 4B1.2 specifically sets apart "use of explosives" from any other "conduct that presents a serious potential risk of physical injury to another." This implies that "possession" of an explosive cannot qualify as a crime of violence under § 4B 1.2; if it did, we would be required to read "use of explosives" out of the Guideline provision. See United States v. Fish, 368 F.3d 1200, 1204 (9th Cir. 2004) ("Interpreting the catchall phrase . . . to cover possession of a `pipe bomb' would render the provision's specific inclusion of `use of explosives' in the same section surplusage."); see also id. at 1205 ("To `use' an explosive, one must first necessarily `possess' it."). For this reason, none of the numerous cases cited by the Government finding mere possession of a firearm, but not an explosive device, to be a crime of violence under § 4B 1.2, is applicable.

Ultimately we, like the District Court and the jury, are limited by the charge in the superseding indictment. Had the indictment charged that the federal crime of violence intended was the use or detonation of a pipe bomb, we would have no difficulty upholding the validity of the jury instruction. Instead, however, the indictment charged Hull with only the intent that his teaching lead to the mere possession of a pipe bomb. The District Court erred in holding that such possession on its own legally constituted a federal crime of violence under 18 U.S.C. § 842(p), or by extension 18 U.S.C. § 16. Accordingly, the judgment of conviction on Count 7 will be vacated.

IV.

Hull next challenges the sufficiency of the evidence on Count 10, witness tampering. Our review is plenary, but deferential inasmuch as "we must . . . consider the evidence in the light most favorable to the verdict and ask whether a reasonable jury could have found that the contested elements were proven beyond a reasonable doubt." United States v. Cohen, 301 F.3d 152, 156-57 (3d Cir. 2002). This is a heavy burden for Hull to meet, United States v. Dent, 149 F.3d 180, 187 (3d Cir. 1998), and he has not done so on appeal.

Hull was convicted under 18 U.S.C. § 1512(b)(1), which penalizes "Whoever knowingly uses intimidation, threatens or corruptly persuades another person, or attempts to do so, or engages in misleading conduct toward another person, with intent to — (1) influence, delay or prevent the testimony of any person in an official proceeding." Specifically, the Government accused Hull of attempting to corruptly persuade Debbie Rusch to testify that she did not believe he was the Unknown Terrorist, when in fact, as she later testified, she did believe he was the Unknown Terrorist; and that he knew the falsehood of his desired testimony.

As to Hull's knowledge, there was ample evidence from which the jury could conclude that Hull knowingly attempted to corruptly persuade Rusch, with the intent to change her testimony. See United States v. Farrell, 126 F.3d 484, 488 (3d Cir. 1997) (holding that "corrupt persuasion" includes "attempting to persuade someone to provide false information to federal investigators"). "[T]he defendant must know that his conduct has the natural and probable effect of interfering with the witness's communication, whether or not it succeeds." United States v. Davis, 183 F.3d 231, 248 (3d Cir. 1999). In his letter telling Rusch to testify on the stand that "I sent [the Unknown Terrorist article] to ya but you don't think I wrote it," Hull told Rusch to immediately burn the letter. Thus, the letter went beyond simply encouraging Rusch not to aid federal investigators, which encouragement alone we excepted from § 1512(b)'s purview under the circumstances of Farrell. We note that, contrary to Hull's assertions on appeal, whether or not the jury had difficulty with certain elements of the charge is ultimately not "proof" that the conviction does not rest on substantial evidence, nor does Hull's explanation that Rusch had a poor memory in need of refreshing somehow justify his suggestion that she testify in a way she affirmatively knew to be untrue. The jury's verdict in Count 10 was supported by substantial evidence.

V.

Hull next renews his attempt to suppress the wiretap interceptions on the ground that agents failed to "minimize" the interceptions and monitoring. Our review of the District Court's factual findings in a suppression hearing is for clear error. United States v. Naranjo, 426 F.3d 221, 226 (3d Cir. 2005). Our review of legal rulings and mixed questions of law and fact is plenary. Id. 18 U.S.C. § 2518(5) requires as follows:

"Every order and extension thereof shall contain a provision that the authorization to intercept shall be executed as soon as practicable, shall be conducted in such a way as to minimize the interception of communications not otherwise subject to interception under this chapter, and must terminate upon attainment of the authorized objective, or in any event in thirty days."

The interception application and order in this case did include a plan to minimize interceptions, as Hull acknowledges. Nonetheless, because some of the intercepted conversations were between Hull and his various girlfriends or Hull and commercial businesses, and because the subject matter included sexual discussions, Hull alleges a failure to minimize in practice. We note, however, that none of the calls Hull labels as "non-pertinent" were played for the jury.

Our inquiry is on the "reasonableness" of minimization efforts, under the totality of the circumstances. Scott v. United States, 436 U.S. 128, 140, 98 S.Ct. 1717, 56 L.Ed.2d 168 (1978); see also United States v. Armocida, 515 F.2d 49 (3d Cir. 1975). We agree with the District Court that when investigating a wide-ranging conspiracy between parties known for their penchant for secrecy, broader interceptions may be warranted. See United States v. Adams, 759 F.2d 1099, 1115 (3d Cir. 1985); Scott, 436 U.S. at 140, 98 S.Ct. 1717 (upholding uninterrupted interceptions in drug conspiracy case). The mere number of intercepted, but non-pertinent, calls is not dispositive. Adams, 759 F.2d at 1115; see also id. ("Appellant also can demonstrate no pattern to the interception of non-pertinent calls. Because of the variety of voices and transactions involved, the government's efforts at minimizing non-pertinent conversations was acceptable."). "The statute does not forbid the interception of all nonrelevant conversations." Scott, 436 U.S. at 140, 98 S.Ct. 1717. Given, for example, the nature of the case and circumstances known to the agents during the interceptions, we discern no error in the District Court's refusal to suppress the wiretap interceptions on the ground of failure to minimize.

VI.

Finally, Hull challenges the jury instructions on Counts 4, 5, and 6, which referred to an unassembled bomb Hull allegedly knowingly made, possessed, and transferred to the confidential informant. "Although we generally review jury instructions for abuse of discretion, our review is plenary when the question is whether a district court's instructions misstated the law." United States v. Dobson, 419 F.3d 231, 236 (3d Cir. 2005) (citations and quotation marks omitted). Hull disputed the jury instructions ultimately given by the District Court, but did not file his own proposed instructions.

Hull was convicted under 26 U.S.C. §§ 5861(d)-(f), which state as follows:

"It shall be unlawful for any person —

[Count 4] (d) to receive or possess a firearm which is not registered to him in the National Firearms Registration and Transfer Record; or

[Count 5] (e) to transfer a firearm in violation of the provisions of this chapter; or

[Count 6] (f) to make a firearm in violation of the provisions of this chapter;"

Specifically, Hull alleges that the jury should have been told that he could only be convicted if (1) he knew that an unassembled bomb was a "firearm" under the applicable statutes; and (2) he intended that the recipient, whom he knew to be an informant, assemble or use the bomb. The District Court's refusal to instruct the jury on these elements, Hull alleges, amounted to an unconstitutional denial of his ability to mount a defense.

The Government was required to prove that Hull knew of the features that made what he was making, possessing, or transferring, a "firearm," Staples v. United States, 511 U.S. 600, 619, 114 S.Ct. 1793, 128 L.Ed.2d 608 (1994), and indeed the District Court instructed the jury accordingly. However, Hull claims that the Government also had to prove that he intended for the unassembled parts of the pipe bomb to be assembled into a fully functioning pipe bomb. This is simply not an element of 26 U.S.C. § 5861. "Section 5861(d) makes no reference to the intent of the person in possession of an unregistered firearm." United States v. Urban, 140 F.3d 229, 232 (3d Cir. 1997).

As Hull concedes, "an unassembled bomb can also qualify . . . as a destructive device," Br. for Appellant at 60, and therefore as a "firearm," for the purposes of 26 U.S.C. §§ 5861. See 26 U.S.C. § 5845(f)(3) (defining as a "firearm," "any combination of parts either designed or intended for use in converting any device into a destructive device as defined [above, including a bomb] and from which a destructive device may be readily assembled"). Hull ignores our previous holding that where there is no "ambiguity . . . as to the nature of the assembled device," intent is irrelevant. Urban, 140 F.3d at 233. Accordingly, we discern no error in the District Court's refusal to instruct the jury that the Government must prove Hull intended that the parts be converted into a destructive device.

VII.

We conclude that Hull's conviction at Count 7 must be vacated, as mere possession of a pipe bomb does not qualify as a "Federal crime of violence" under 18 U.S.C. § 842(p). We will affirm the judgment of conviction on all other Counts.