Legal Details
Undetectable Firearms Act
Photo by Jan Beránek (CC BY-SA 3.0)
| Identification | |
|---|---|
Citation | 18 U.S.C. § 922(p) |
| Code Sections |
|
| Jurisdiction | |
Territory | United States (Federal) |
Enacted By | United States Congress |
Administered By | Bureau of Alcohol, Tobacco, Firearms and Explosives |
| Timeline | |
Signed | 1988 |
| Key Provisions | |
| |
| Applicability | |
| Applies To | All persons manufacturing, importing, selling, shipping, delivering, possessing, transferring, or receiving firearms |
| Exemptions |
|
| Penalties | Federal criminal penalties including potential prison time |
Legislative History | |
1988Undetectable Firearms Act enacted in response to concerns about polymer-framed pistols entering the U.S. market 2024Most recent congressional renewal of the Act | |
| Major Amendments | |
2024Most recent renewal of the Act by Congress | |
Undetectable Firearms Act
Legal information and analysis
From The Boise Gun Club Handbook
Disclaimer: This is educational information only, not legal advice. Always consult with a qualified attorney for legal guidance.
The Undetectable Firearms Act makes it a federal crime to manufacture, import, sell, ship, deliver, possess, transfer, or receive any firearm that can't be spotted by standard security equipment--and with 3D printing getting cheaper every year, this 36-year-old law matters more than when Congress first wrote it.
- Detection requirements: Must trigger metal detectors AND show up on X-ray machines
- Real target: Deliberately undetectable weapons, not your polymer-framed carry gun
- Penalties: Federal charges with serious prison time
This whole thing started back in 1988 when Glock hit the market and politicians lost their minds over "plastic guns." Never mind that every Glock has a steel barrel, slide, springs, and enough metal to light up a detector from across the room.
What Makes a Gun "Undetectable"edit
Legal Detection Standards
Legal detection requirements - both metal detector AND X-ray tests must pass
The legal reality: Under 18 USC § 922(p), every firearm must contain enough metal to trigger both walk-through metal detectors AND show up clearly on X-ray screening equipment. We're not just talking airports--courthouses, government buildings, anywhere they run security.
The detection standard has two parts that both have to be met. Your gun needs enough metal content for reliable identification by the equipment they actually use at security checkpoints.
| Detection Method | Requirement | Purpose |
|---|---|---|
| Walk-through Metal Detectors | Must trigger alarm | Identifies metal content during screening |
| X-ray Screening | Must show clear image | Reveals firearm shape and components |
| Combined Standard | Both methods required | Ensures reliable detection by security equipment |
The detection standard requires BOTH metal detector triggering AND X-ray visibility - not just one or the other.
Commercial Firearms Compliance
Most factory firearms blow past this requirement without even trying. Your Glock, M&P, XD--all have steel barrels, slides, springs, and fire control parts. Even rifles with polymer stocks and handguards pack plenty of metal in the action.
Who This Actually Affectsedit
3D Printing Impact
Modern 3D printing gave this old law new teeth. You can print receiver components, grip frames, even simple single-shot designs entirely in plastic. But here's the thing--even basic functional firearms need metal parts to work reliably.
What this means for you: If you're buying commercial guns or building standard designs, you're already compliant. This law catches people trying to make deliberately undetectable weapons or those who don't understand what "detectable" actually means.
Prohibited Activities
The law covers every step:
| Prohibited Activity | Legal Definition | Penalty |
|---|---|---|
| Manufacturing | Building/assembling undetectable firearm | Federal charges |
| Importing | Bringing into United States | Federal charges |
| Selling/Transferring | Changing possession to another party | Federal charges |
| Possessing | Having in custody or control | Federal charges |
Common Misconceptionsedit
People get confused because this touches both technical and legal ground. Here's what's actually true:
- "Glocks are plastic guns" - Wrong. Every polymer-framed pistol has steel barrel, slide, and metal parts exceeding detection requirements
- "Only applies to 3D printed guns" - Incorrect. Any undetectable firearm violates the law regardless of construction method
- "Add any metal piece and you're legal" - False. Metal content must enable reliable detection by standard security equipment
Exceptions and Enforcementedit
Authorized Exceptions
| Exception Category | Who Qualifies | Requirements |
|---|---|---|
| Government Agencies | Military, federal/state/local law enforcement | Official authorization required |
| Government Contractors | Companies with direct agency contracts | Must be working on authorized projects |
| Maintenance Exception | Any lawful owner | Temporary disassembly for cleaning/repair only |
Federal Penalties
Congress keeps renewing this thing because nobody wants to be the politician who voted to allow undetectable guns. Most recent renewal was 2024, and it'll get renewed again when it comes up.
Violations carry federal charges--we're talking potential prison time, not fines. The ATF doesn't mess around with firearms violations, especially ones involving security concerns.
Practical Realityedit
Compliance for Most Owners
For 99% of gun owners, this law is invisible. You buy factory guns or build standard designs with normal parts, and you're automatically compliant. The law mainly catches people either deliberately trying to evade security or those who misunderstood the requirements.
The rise of 3D printing put this back in the spotlight. You can print sophisticated components now, but making a completely undetectable gun is both illegal and impractical.
Even basic functionality requires metal springs, firing pins, and usually barrels.
Manufacturing Considerations
If you're getting into manufacturing or experimenting with materials, think carefully. The detection requirements are about reliable identification by security equipment--not just technically containing some metal somewhere.
Stick to proven designs using standard materials and this law will never affect you. Start experimenting with minimal-metal builds and you're potentially looking at federal charges.
Decision tree showing compliance paths for different firearm construction methods
This information is provided for educational purposes only and does not constitute legal advice. Gun laws are complex and change frequently. Always consult with a qualified attorney for legal guidance specific to your situation.
Last Updated: 2026-01-15
See Alsoedit
- Ace Hardware of Sandusky(Sandusky, MI)
- New Philly Sportsman Specialities(New Philadelphia, OH)
- Atwoods Ranch & Home #46(LACY LAKEVIEW, TX)
- G & P Distributors(McConnellsburg, PA)
This is not legal advice
This guide provides general information about federal and state firearms laws based on publicly available statutes. Laws change frequently and vary significantly by state. Always verify current laws in your jurisdiction. Consult a qualified attorney for legal advice on your specific situation. When in doubt, contact local law enforcement or state police.
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