How Do Federal and State Gun Laws Work Together?

Why It Matters

The dual federal-state system creates a patchwork of laws that varies dramatically by location. A firearm configuration that is perfectly legal in Arizona may be a felony in California. An accessory that is legal under federal law may be banned by your state. Understanding how these layers interact prevents accidental felonies and ensures you exercise your rights within the law.

The Detail

Federal firearms law basics (apply everywhere in the US):

Gun Control Act of 1968 (GCA):
- Establishes the Federal Firearms License (FFL) system
- Prohibits interstate sales of handguns (must go through an FFL in buyer's state)
- Long guns can be purchased in any state from an FFL
- Prohibited persons cannot possess firearms (felons, domestic violence convictions, drug users, adjudicated mentally ill, illegal aliens, dishonorably discharged, under restraining order)
- Establishes minimum ages: 18 for long guns, 21 for handguns from an FFL

National Firearms Act of 1934 (NFA):
- Regulates SBRs, SBSs, suppressors, machine guns, AOWs, destructive devices
- Requires registration and $200 tax stamp
- States can further restrict or ban NFA items entirely

Brady Handgun Violence Prevention Act (1993):
- Established the NICS background check system
- Required for all sales through FFLs
- Private sales between residents of the same state do not require federal background check (but many states require them)

Firearm Owners Protection Act (FOPA — 1986):
- Protects interstate transport of legal firearms
- Banned new machine gun registration for civilians (Hughes Amendment)
- Prohibits a national firearms registry

How states add restrictions:
- Magazine capacity limits (10, 15, or no limit)
- Assault weapon bans (feature-based or named models)
- Waiting periods (0 to 10 days)
- Permit requirements to purchase or possess
- Universal background check requirements for private sales
- Red flag / ERPO (Extreme Risk Protection Order) laws
- Open carry restrictions
- Concealed carry permit requirements or constitutional carry
- Ammunition purchase restrictions
- Storage requirements

Examples of federal-state interaction:
- Suppressors: legal under federal law (with NFA tax stamp), banned in 8 states
- Magazines over 10 rounds: legal under federal law, banned in approximately 12 states
- AR-15s: legal under federal law, restricted by features in approximately 7 states
- Private sales without background check: legal under federal law in most states, but approximately 22 states require universal background checks
- Concealed carry without permit: no federal position, 29 states allow it

Preemption:
- Some states have preemption laws preventing cities from passing gun laws stricter than state law (Texas, Florida, Pennsylvania)
- Other states allow local jurisdictions to add restrictions (California, New York, Illinois)
- If your state lacks preemption, check city and county laws in addition to state law

Build Impact

Before buying, building, or carrying any firearm: know your state laws first, then confirm federal compliance. Use resources like Handgunlaw.us, USCCA reciprocity maps, and your state's firearms owners association for current information. Laws change frequently through legislation, ballot initiatives, and court rulings. If you move to a new state, research firearms laws BEFORE you transport your collection — you may need to modify, register, or surrender certain items.