At issue is whether Castillo v. United States, 530 U.S. 120, 120 S.Ct. 2090, 147 L.Ed.2d 94 (2000), applies retroactively on collateral review. We conclude that Castillo announced a new procedural rule that *417is not retroactive under Teague v. Lane, 489 U.S. 288, 109 S.Ct. 1060, 103 L.Ed.2d 334 (1989). We therefore affirm the denial of Enrique Gonzales’s motion for relief from sentence under 28 U.S.C. § 2255.
I.
Gonzales was convicted of several drug trafficking and firearms charges, including one count of carrying a firearm in violation of 18 U.S.C. § 924(c)(1). For the § 924(c)(1) count, the indictment referred to a generic “firearm” but did not specify that Gonzales carried a maehinegun. With jury instructions that mirrored the indictment, the jury convicted Gonzales of all counts.
The government then filed a motion seeking a thirty-year sentence on the § 924(c)(1) count. At the time, § 924(c)(1) imposed a five-year sentence for carrying an ordinary firearm, but a thirty-year sentence for carrying a maehinegun.1 The court granted the motion, finding that Gonzales had carried a maehinegun, and sentenced him to thirty-years’ imprisonment on the § 924(c)(1) count.2 We affirmed. United States v. Gonzales, 121 F.3d 928 (5th Cir.1997), cert. denied, 522 U.S. 1181, 118 S.Ct. 1084, 140 L.Ed.2d 141 (1998).
Gonzales then filed a § 2255 motion to correct the sentence on the § 924(c)(1) count. Following Castillo and Apprendi v. New Jersey, 530 U.S. 466, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000), he argues that his sentence violates his Fifth and Sixth Amendment rights, because the indictment did not allege, and the jury did not find beyond a reasonable doubt, that the firearm was a maehinegun. The district court denied the motion, holding that Apprendi and Castillo announce new procedural rules that are not retroactive under Teag-ue. See Gonzales v. United States, 159 F.Supp.2d 555 (S.D.Tex.2001). Because of their importance, the court granted a certificate of appealability on both questions.
II.
Gonzales seeks collateral relief from his sentence based on the rules of Apprendi and Castillo. Because there are no disputed facts, we review the denial of the § 2255 motion de novo. United States v. Willis, 273 F.3d 592, 595 (5th Cir.2001).
These rules are “new” as to Gonzales, because his conviction and sentence were final before the Supreme Court decided either Apprendi or Castillo. Some new rules apply retroactively on collateral review, others not. If a new rule is substantive, i.e., if it interprets the meaning of a criminal statute, it always applies retroactively. Davis v. United States, 417 U.S. 333, 94 S.Ct. 2298, 41 L.Ed.2d 109 (1974). If it is procedural, however, it applies retroactively only if it fits one of the Teague exceptions: (1) “[I]t places certain kinds of primary, private individual conduct beyond the power of the criminal law-making authority to proscribe,” or (2) “it requires the observance of those procedures that are implicit in the concept of ordered liberty.” *418Teague, 489 U.S. at 311, 109 S.Ct. 1060 (quotation marks and alterations omitted).
Gonzales argues that Apprendi and Castillo announced substantive rules that necessarily apply retroactively. In the alternative, he contends that these rules fit the second Teague exception if they are procedural. After briefing was completed in this case, we held in United States v. Brown, 305 F.3d 304 (5th Cir.2002), that Apprendi announced a non-retroactive procedural rule; we now conclude that Castillo did the same.
A.
In Castillo, 530 U.S. at 131, 120 S.Ct. 2090, the Court held that “Congress intended the firearm type-related words it used in § 924(c)(1) to refer to an element of a separate, aggravated crime.” Gonzales argues that this rule is substantive and therefore applies retroactively to his sentence.3 To the contrary, the rule of Castillo is procedural, because its functional effect is to shift fact-finding responsibility from judge to jury, not to alter the meaning of the fact to be found.
The Supreme Court explained the “distinction between substance and procedure ... in the habeas context” in Bousley v. United States, 523 U.S. 614, 620, 118 S.Ct. 1604, 140 L.Ed.2d 828 (1998): “[0]ne of the ‘principal functions of habeas corpus is to assure that no man has been incarcerated under a procedure which creates an impermissibly large risk that the innocent will be convicted’ ” (quoting Teague, 489 U.S. at 312, 109 S.Ct. 1060) (alteration omitted).
A procedural rule, in other words, ensures “an accurate conviction” of conduct that the law criminalizes. Id. (quoting Teague, 489 U.S. at 313, 109 S.Ct. 1060). A substantive rule, on the other hand, involves a “deeision[] of [a court] holding that a substantive federal criminal statute does not reach certain conduct.” Id. That is, a substantive rule interprets a federal criminal statute to determine what conduct the law in fact criminalizes.
We recently applied this distinction in Brown. In Apprendi, 530 U.S. at 476, 120 S.Ct. 2348, the Court held that “any fact (other than prior conviction) that increases the maximum penalty for a crime must be charged in an indictment, submitted to a jury, and proven beyond a reasonable doubt” (quoting Jones v. United States, 526 U.S. 227, 243 n. 6, 119 S.Ct. 1215, 143 L.Ed.2d 311 (1999)). We explained in Brown, 305 F.3d at 309, that this rule “did not change what the government must prove, only that the jury, rather than the judge must decide the [relevant factual] question.” We also emphasized that the Apprendi Court characterized its decision as procedural. Id. at 308.4
We acknowledge that Castillo, unlike Apprendi, does not sound very much like a ruling on constitutional criminal procedure. The term “procedure” or its cognates do not appear in Castillo. Likewise, the *419Court neither cites nor mentions the Fifth or Sixth Amendment.
Indeed, Castillo reads very much like an ordinary statutory-interpretation decision. For example, the Court framed the question as “whether Congress intended the statutory references to particular firearm types in § 924(c)(1) to define a separate crime or simply to authorize an enhanced penalty.” Castillo, 530 U.S. at 123, 120 S.Ct. 2090. The Court’s answer was that “even apart from the doctrine of constitutional doubt, our consideration of § 924(c)(l)’s language, structure, context, history, and such other factors as typically help courts determine a statute’s objectives, leads us to conclude that the relevant words create a separate substantive crime.” Id. at 124, 120 S.Ct. 2090 (emphasis added). Tools such as text, structure, and history are, of course, the hallmarks of statutory interpretation.
Castillo therefore appears, at first blush, to announce a substantive rule, as the only circuit to address the question has concluded. In United States v. Wiseman, 297 F.3d 975, 981-82 (10th Cir.2002), the court held that “[t]he Castillo court did not announce a new constitutional rule of criminal procedure; it construed a criminal statute to require a jury determination on the type of firearm used by the defendant.” The Wiseman court reasoned that the rule must be substantive, because “[t]he Court’s holding in Castillo was based solely on its interpretation of § 924(c)(1).” Id. at 981 (emphasis added).
We reason, nonetheless, that Castillo announced a procedural rule. We recognize that this conclusion may seem coun-terintuitive. After all, the Court interpreted § 924(c)(1) and held that its “firearm type-related words ... [are] an element of a separate, aggravated crime.” Castillo, 530 U.S. at 131, 120 S.Ct. 2090 (emphasis added). Calling a statutory term an “element” was once a telltale sign of a substantive interpretation of a criminal statute.
After Apprendi, however, we no longer can assume that an interpretation of a statute’s “elements” is substantive. The distinction between what was once called an “element” and what was once called a “sentencing factor” “is largely irrelevant after Apprendi.” United States v. Matthews, 312 F.3d 652, 662 (5th Cir.2002), cert. denied, — U.S. -, 123 S.Ct. 1604, 155 L.Ed.2d 341 (2003). These terms now reflect the allocation of fact-finding responsibility between judge and jury. By calling the “firearm type-related words” of § 924(c)(1) an “element,” the Court allocated responsibility for finding this fact to the jury. It did not alter the substantive meaning of the “firearm type-related words.”
The terms “element” and “sentencing factor” are therefore conclusions, not reasons for a conclusion.5 The rule of Ap-*420prendí, to repeat, is that “any fact (other than prior conviction) that increases the maximum penalty for a crime must be charged in an indictment, submitted to a jury, and proven beyond a reasonable doubt.” Apprendi, 530 U.S. at 476, 120 S.Ct. 2348 (quoting Jones, 526 U.S. at 243 n. 6, 119 S.Ct. 1215). Apprendi thus requires courts to determine the statute’s basic offense and its maximum penalty, and then to determine what other facts in the statute affect the possible penalty.
If these facts do not increase the maximum, they may be found by a judge; if they do, they must be alleged in the indictment and found by a jury. At this point, the court, as a shorthand for its reasoning, may attach the term “sentencing factor” to the former and “element” to the latter. Cf. Castillo, 530 U.S. at 123-24, 120 S.Ct. 2090. What matters, though, is the effect of a fact on the statutory maximum.
This Apprendi analysis can resemble substantive statutory interpretation, because the court must use traditional tools to identify the basic offense and its penalty, as well as any facts that affect the penalty. The Court in Castillo engaged, albeit implicitly, in precisely this kind of Apprendi analysis.6
The Castillo Court, 530 U.S. at 124, 120 S.Ct. 2090, used the text and structure of § 924(c)(1) to identify “the basic federal offense of using or carrying a gun during and in relation to a crime of violence [or drug trafficking crime],” which carried a five-year sentence. The Court then relied on this and other tools to decide that the kind of firearm used or carried is a fact that increases the statutory maximum. Id. at 125-31, 120 S.Ct. 2090. The Court concluded by calling this fact “an element of a separate, aggravated crime.” Id. at 131, 120 S.Ct. 2090. As the Court’s reasoning demonstrates, though, the conclu-sional term “element” merely means that “the indictment must identify the firearm type and a jury must find that element proved beyond a reasonable doubt.” Id. at 123,120 S.Ct. 2090.
In other words, Apprendi analysis does not alter the meaning of the fact to be found, but instead allocates fact-finding responsibilities between judge and jury. Consider Gonzales’s eligibility for a thirty-year sentence under § 924(c)(1) before and after Castillo. In both instances, someone had to find that he carried a machinegun, not a simple firearm. The only difference, after Castillo, is that, for the thirty-year sentence to be imposed, the jury, not the court, must find this fact.
The opening sentence reveals this truth: “In this case we once again decide whether words in a federal criminal statute create offense elements (determined by a jury) or sentencing factors (determined by a judge).” Castillo, 530 U.S. at 121, 120 S.Ct. 2090. And, as we explained in Brown, 305 F.3d at 309, the responsibility for fact-finding is a quintessential procedural rule, not “a substantive change in the law.”
*421It is useful, in this regard, to contrast Castillo with Bailey v. United States, 516 U.S. 137, 116 S.Ct. 501, 133 L.Ed.2d 472 (1995). There, the Court interpreted the meaning of “use” in § 924(c)(1) to mean “active employment of the firearm by the defendant.” Id. at 143, 116 S.Ct. 501. The Court contrasted this definition with “mere possession of a firearm by a person who commits a drug offense.” Id. Unlike Castillo, Bailey therefore altered the substantive meaning of a key term in § 924(c)(1), as the federal courts quickly learned from the avalanche of § 2255 motions. Thus, Bailey necessarily applied retroactively on collateral review. Bousley, 523 U.S. at 620, 118 S.Ct. 1604.
Finally, our precedents support the view that Castillo announced a procedural rule. In United States v. Shunk, 113 F.3d 31 (5th Cir.1997), we concluded that United States v. Gaudin, 515 U.S. 506, 115 S.Ct. 2310, 132 L.Ed.2d 444 (1995), announced a procedural rule. In Gaudin, id. at 511, 115 S.Ct. 2310, the Court had held that the materiality element of 18 U.S.C. § 1001 had to be found by the jury, not the court. We noted that “Gaudin explicitly states that the rule it created was procedural.” Shunk, 113 F.3d at 35. More importantly, however, we also explained that “Gaudin did not change what the Government must prove; materiality was always an element of a § 1001 offense. Instead, Gaudin changed the party to whom the Government must prove materiality — from judge to jury.” Id. (citation omitted).
Likewise, Castillo did not change the necessary factual showing for a thirty-year sentence under § 924(c)(1). The government always had to prove that the firearm used was a machinegun; Castillo merely changed “the party to whom the government must prove” that the firearm used was a machinegun.7
Even United States v. McPhail, 112 F.3d 197 (5th Cir.1997), in which we concluded (before Bousley) that Bailey announced a substantive rule, indicates, by way of contrast, that Castillo announced a procedural rule. The McPhail court explained, in three different ways, why the rule of Bailey was substantive. Most basically, the “decision in Bailey articulates the substantive elements” of the conduct criminalized by § 924(c)(1). McPhail, 112 F.3d at 199. That is to say, Bailey “explains what conduct is, and always has been, criminalized by [§ 924(c)(1)].” Id. This kind of holding “is a substantive, non-constitutional decision concerning the reach of a federal statute.” Id.
These explanations all accurately portray the rule of Bailey but not of Castillo. In Castillo the Court did not articulate the elements of § 924(c)(1), or explain what conduct it criminalizes, or affect its reach. Unlike Bailey, therefore, Castillo announced a procedural rule.8
In sum, Castillo shifted the fact-finding responsibility from judge to jury but did not alter the meaning of the fact to be found. Castillo does not determine what *422conduct the law criminalizes, but rather tends to ensure an accurate conviction of and sentence for conduct that the law criminalizes. Both before and after Castillo, § 924(c)(1) imposed a thirty-year sentence for using or carrying a machinegun during a drug trafficking crime, but Castillo now tends to ensure that these sentences will be imposed in a more accurate fashion.
The Court’s unavoidable use of traditional statutory-interpretation tools may efface this critical distinction — so much so that the Tenth Circuit mistakenly held in Wise-man that the rule of Castillo is substantive9 — but the Supreme Court’s analysis undermines neither the distinction nor the reasoning of Brown, Shunk, and McPhail. Thus, Castillo is a procedural rule subject to the Teague framework.
B.
Gonzales argues, in the alternative, that the rule of Castillo fits within the second Teague exception, which makes retroactive new procedural rules that “require[] the observance of those procedures that are implicit in the concept of ordered liberty.” Teague, 489 U.S. at 311, 109 S.Ct. 1060 (quotation marks and alteration omitted). The Court described such rules as “watershed rules of criminal procedure,” id., that are “central to an accurate determination of innocence or guilt,” id. at 313,109 S.Ct. 1060. Because we are confident that the rule of Castillo is not a watershed rule of criminal procedure, we decline to apply it retroactively.
Castillo is nothing more than a particular manifestation of Apprendi. See Torres, 282 F.3d at 1246 (observing that Castillo belongs to “the Apprendi family of cases”). Apprendi requires any fact that increases the statutory maximum to be alleged in the indictment and proven to the jury beyond a reasonable doubt. Castillo requires that the kind of firearm used in a § 924(c)(1) offense be alleged in the indictment and proven to the jury beyond a reasonable doubt. Gonzales more or less admits this point, because he relies on Apprendi and Castillo for the same arguments.
In Broum, 305 F.3d at 309-10, we held that Apprendi is not a watershed rule of criminal procedure. We reasoned that Ap-prendi improves the accuracy of the sentence, not the determination of guilt or innocence of the offense, and does not alter our understanding of the bedrock elements essential to a fundamentally fair proceeding. Id. at 309. This reasoning also applies to Castillo, which neither affects the accuracy of the determination of guilt or innocence of a § 924(c)(1) offense nor reworks our basic understanding of “ordered liberty.”10 In short, if the general rule of Apprendi does not fit the second Teague exception, nor does a particular manifestation of that rule in Castillo.
The order denying the § 2255 motion is AFFIRMED.
. "Whoever, during and in relation to any ... drug trafficking crime ... uses or carries a firearm, shall, in addition to the punishment provided for such ... drug trafficking crime, be sentenced to imprisonment for five years, ... and if the firearm is a maehinegun, ... to imprisonment for thirty years.” 18 U.S.C. § 924(c)(1) (1994). Congress since has amended § 924(c)(1).
. The jury also had found Gonzales guilty of possession of a maehinegun in violation of 18 U.S.C. § 922(o )(1). The indictment and jury instructions for this count specified that Gonzales’s firearm was a maehinegun. There was no evidence of another firearm involved in Gonzales's crimes.
.If the rule of Castillo is substantive, hence retroactive, Gonzales would be entitled to relief from sentence, because his sentence plainly violates the rule. Under Castillo, he was eligible for the thirty-year sentence only if his firearm was a machinegun, but this essential fact was not alleged in the indictment or contained in the jury instruction. See Castillo, 530 U.S. at 123, 120 S.Ct. 2090 (explaining that the fact must be alleged in the indictment and proved to the jury beyond a reasonable doubt).
.See, e.g., Apprendi, 530 U.S. at 475, 120-S.Ct. 2348 (“The substantive basis for New Jersey's enhancement is thus not at issue; the adequacy of New Jersey's procedure is.”); id. at 484, 120 S.Ct. 2348 (stating that "the reasonable doubt requirement has a vital role in our criminal procedure for cogent reasons”) (quotation marks omitted).
. "Apprendi repeatedly disparaged the distinction between a fact characterized as a sentencing factor and a fact characterized as an element of a separate offense when the fact increases the statutory maximum penalty.” Matthews, 312 F.3d at 662 & n. 13 (collecting quotations). The Supreme Court has reiterated this principle in subsequent Apprendi cases.
"As to elevation of the maximum punishment ... Apprendi repeatedly instructs in that context that the characterization of a fact or circumstance as an ‘element’ or a 'sentencing factor' is not determinative of the question 'who decides,' judge or jury.” Ring v. Arizona, 536 U.S. 584, 122 S.Ct. 2428, 2441, 153 L.Ed.2d 556 (2002). "[T]he fundamental meaning of the jury-trial guarantee of the Sixth Amendment is that all facts essential to imposition of the level of punishment that the defendant receives — whether the statute calls them elements of the offense, sentencing factors, or Mary Jane — must be found by the jury *420beyond a reasonable doubt.” Id. at 2444 (Scalia, J., concurring).
. We recognize that Castillo preceded Appren-di by three weeks. We sometimes emphasize Apprendi, however, because it addresses the same issue, i.e., the constitutional allocation of fact-finding responsibility, more generally and thoroughly than does Castillo. Moreover, the Court grappled with this issue repeatedly before deciding Castillo and Appren-di. See, e.g., Jones v. United States, 526 U.S. 227, 119 S.Ct. 1215, 143 L.Ed.2d 311 (1999); Almendarez-Torres v. United States, 523 U.S. 224, 118 S.Ct. 1219, 140 L.Ed.2d 350 (1998). Thus, we safely may assume the Court had all its caselaw in mind when it issued Castillo and Apprendi. See United States v. Torres, 282 F.3d 1241, 1246 (10th Cir.2002) (observing that Castillo belongs to "the Apprendi family of cases”).
. By holding that Gaudin announced a procedural rule, Shunk also supports what might seem a peculiar proposition: The rule of a case may be procedural even if that rule applies only to a single statute.
. See also United States v. Lopez, 248 F.3d 427, 432 (5th Cir.) (relying on these three passages from McPhail to conclude that Richardson v. United States, 526 U.S. 813, 119 S.Ct. 1707, 143 L.Ed.2d 985 (1999), announced a substantive rule regarding the scope of 21 U.S.C. § 848(a)), cert. denied, 534 U.S. 898, 122 S.Ct. 222, 151 L.Ed.2d 158 (2001). Irrespective of whether Lopez's reading of Richardson is correct, Lopez does not purport to apply a test different from that of Bousley, McPhail, and Shunk, and, in any event, McPhail and Shunk, like Bousley, pre*422ceded Lopez and hence remain binding on this panel.
. The Tenth Circuit contradicted itself in the key sentence of Wiseman: “The Castillo Court did not announce a new constitutional rule of criminal procedure; it construed a criminal statute to require a jury determination on the type of firearm used by the defendant.” Wise-man, 297 F.3d at 981-82. The clause before the semicolon states that Castillo did not announce a procedural rule, but the clause after the semicolon describes a procedural rule.
. See Shunk, 113 F.3d at 37 ("[0]ne can easily envision a system of 'ordered liberty' in which certain elements of a crime can or must be proved to a judge, not to a jury.”).