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Fourth Circuit Limits the Guidelines Enhancement for Firearms with Altered Serial Numbers

The Fourth Circuit’s ruling on the altered serial number enhancement narrows how federal courts sentence firearms offenses involving damaged markings. In United States v. Smith, No. 25-4065 (4th Cir. Aug. 25, 2026), the court held that the four-level enhancement under U.S.S.G. § 2K2.1(b)(4)(B)(i) does not apply merely because one or more serial-number markings on a firearm have been rendered illegible. Instead, the altered serial number enhancement now turns on whether the firearm itself remains traceable — a distinction that can substantially affect a defendant’s Guidelines range.

altered serial number enhancement

The Facts

Markel Smith was prosecuted after police recovered several firearms from a vehicle, including a Glock equipped with a machinegun conversion device, commonly called a “switch.” Smith ultimately pleaded guilty to possessing a “machinegun” in violation of 18 U.S.C. § 922(o).

The Glock presented an unusual sentencing issue. Its serial number appeared in three places. Two of those markings had been scratched to the point that most of the characters could no longer be read. But the third remained completely intact.

At sentencing, the district court nevertheless applied § 2K2.1(b)(4)(B)(i), which adds four offense levels when a firearm has a serial number modified so that the original information is “illegible or unrecognizable to the unaided eye.” (The defendant need not be the one who modified it). With the enhancement, Smith’s advisory range was 57 to 71 months, and the court sentenced him to 57 months.

The Fourth Circuit reversed. The key to the majority’s decision was the Sentencing Commission’s 2024 amendment to § 2K2.1. Before that amendment, the Guideline applied when a firearm had an “altered or obliterated serial number,” regardless of whether other serial numbers on the firearm remained intact. The amended language instead asks whether the serial number was modified so that the “original information” is illegible or unrecognizable to the unaided eye. The Commission adopted that language to resolve a circuit split over how badly a serial number must be damaged before the enhancement applies.

The Court's Analysis

The Fourth Circuit read the new language narrowly. In its view, the purpose of the enhancement is not simply to impose additional punishment whenever someone has tampered with a serial-number marking. Federal statutes separately criminalize that conduct. Rather, the enhancement addresses the additional problem created by an untraceable firearm.

The court therefore announced a straightforward rule: § 2K2.1(b)(4)(B)(i) applies only when modification of the serial numbers leaves the firearm no longer traceable. The Government bears the burden of proving that fact by a preponderance of the evidence.

That burden could not be met in Smith’s case. Although two markings had been damaged, a third displayed the complete serial number—“AGGE159”—and law enforcement had actually used it to trace the Glock. The Fourth Circuit vacated Smith’s sentence and remanded for resentencing without the four-level enhancement. Given the original sentence of 57 months and all other aspects of the sentencing remaining the same, a four-level reduction is likely to result in a roughly 37-month sentence.

Key Takeaway

In short, Smith changes the focus of objections to this enhancement. It is no longer enough for the Government to show that a serial number has been scratched, ground down, or otherwise made unreadable. Defense counsel should examine the entire firearm, determine whether the serial number appears elsewhere, and—importantly—determine whether ATF or another agency was actually able to trace it.

The decision also creates a circuit conflict. Judge Agee dissented from the Guidelines ruling, noting that the Third Circuit recently reached the opposite conclusion under the amended Guideline in United States v. Craddock, 179 F.4th 156 (3rd Cir. 2026). He would have held that a single illegible serial-number marking is enough, even if another iteration remains perfectly legible.

One Final Point

Smith does not provide relief from prosecutions involving Glock switches themselves. The court unanimously rejected Smith’s Second Amendment challenge to § 922(o), reiterating Fourth Circuit precedent that machineguns are outside the Second Amendment’s protection.

But on the sentencing issue, Smith is significant. In the Fourth Circuit, the question after today is not simply whether a serial number was altered. The question is whether the gun could still be traced.

 Disclaimer:  This case summary is provided for informational purposes only and does not constitute legal advice. Polales Horton & Leonardi LLP is experienced in handling a wide variety of civil and criminal cases in state and federal courts. To discuss your case, please contact Dan Leonardi at dleonardi@phl-firm.com.

 

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