Type 4 explosives magazine requirements come from the ATF under 27 CFR Part 555, and they cover four things at once: what you’re allowed to store, how the magazine is built and locked, where you can place it, and what paperwork you keep. A Type 4 magazine is authorized for low explosives and blasting agents, must be fire-resistant and theft-resistant (weather-resistant too if it sits outdoors), and can take the form of a permanent building, an igloo, a tunnel, a dugout, a box, a trailer, or a semitrailer.1eCFR. 27 CFR 555.210 – Construction of Type 4 Magazines Getting any of it wrong exposes you to fines up to $250,000 and up to ten years in federal prison.
What You Can Store in a Type 4 Magazine
Low explosives deflagrate rather than detonate. The federal classification includes black powder, safety fuses, igniters, igniter cords, fuse lighters, and display fireworks classified under U.S. Department of Transportation designations UN0333, UN0334, or UN0335.2eCFR. 27 CFR 555.202 – Classes of Explosive Materials Blasting agents such as ammonium nitrate-fuel oil mixtures are also permitted.3eCFR. 27 CFR 555.203 – Types of Magazines
High explosives like dynamite, flash powders, and bulk salutes are not allowed. Those require a Type 1 or Type 2 structure. Detonators that will not mass detonate can go in a Type 4 magazine if stored in a magazine separate from other explosive materials, and inside that separate Type 4 they can share space with electric squibs, safety fuse, shock tube, igniters, and igniter cord.1eCFR. 27 CFR 555.210 – Construction of Type 4 Magazines
Indoor magazines are capped at 50 pounds of low explosives total. That cap applies across every indoor magazine in the same building, not per magazine. Electric detonators stored indoors are limited to 5,000 units in a separate magazine.4eCFR. 27 CFR 555.210 – Construction of Type 4 Magazines No indoor Type 4 magazine may be placed inside a residence or dwelling. Outdoor magazines have no fixed poundage cap in the Type 4 construction rules, but any single magazine is limited to 300,000 pounds of explosive materials unless the ATF Director approves more.
Construction Standards
Walls and floors of an outdoor Type 4 magazine must be built from masonry, metal-covered wood, fabricated metal, or a combination of those materials, with walls and floors constructed from or covered with nonsparking material or lattice work. Doors must be metal or solid wood covered with metal. If the magazine sits on piers or posts rather than a continuous foundation, the open space underneath has to be enclosed with fire-resistant material. The ground around the magazine must slope away for drainage, or you need another effective drainage arrangement.1eCFR. 27 CFR 555.210 – Construction of Type 4 Magazines
Trailers and semitrailers used as magazines must have wheels removed or be effectively immobilized with kingpin locking devices or another ATF-approved method whenever left unattended. Parking and walking away is not enough.
Indoor magazines follow the same wall, floor, and door material rules, but they don’t need the lattice work and don’t need independent weather protection if the host building already provides it. Hinges and hasps on any Type 4 magazine door must be welded, riveted, or bolted with nuts on the inside so they can’t be removed when the door is closed and locked.
Lock and Door Hardware
Every door on a Type 4 magazine has to use one of five lock arrangements:
- Two mortise locks
- Two padlocks fastened in separate hasps and staples
- One mortise lock and one padlock
- A mortise lock that requires two keys to open
- A three-point lock
Any padlock must have at least five tumblers and a case-hardened shackle no smaller than 3/8 inch in diameter. Padlocks have to be shielded by steel hoods at least 1/4 inch thick, shaped to block sawing or prying at the locks, hasps, and staples. The steel-hood rule doesn’t apply if the door is secured from the inside by a bolt, lock, or bar that can’t be operated from outside.4eCFR. 27 CFR 555.210 – Construction of Type 4 Magazines
An indoor magazine inside a room that is already secured to the same locking standard gets an easier rule: a single steel padlock meeting the five-tumbler, 3/8-inch shackle specification, no steel hood required.
Lighting Rules
Battery-activated safety lights and lanterns are allowed inside any explosives magazine. Hardwired electric lighting has to meet the National Electrical Code (NFPA 70) standards appropriate for conditions inside the magazine, and every electrical switch has to be located outside the magazine and also meet the code.5eCFR. 27 CFR 555.217 – Lighting Keep copies of invoices or work orders that show the installation is compliant, because ATF inspectors ask for them.
Placement and Distance to Buildings, Roads, and Other Magazines
27 CFR 555.219 sets the distance table specifically for low explosives stored in Type 4 magazines. Required standoff scales with the total weight of explosive materials in the magazine, measured against inhabited buildings, public highways, passenger railways, and other magazines. A few representative weight bands:
- Up to 1,000 pounds: 75 feet from inhabited buildings and public roads, 50 feet from another above-ground magazine
- 1,000 to 5,000 pounds: 115 feet from buildings and roads, 75 feet between magazines
- 5,000 to 10,000 pounds: 150 feet from buildings and roads, 100 feet between magazines
- 100,000 to 200,000 pounds: 375 feet from buildings and roads, 250 feet between magazines
The table continues up to 300,000 pounds.6eCFR. 27 CFR 555.219 – Table of Distances for Storage of Low Explosives When multiple magazines on the same property sit closer together than the required separation distance, ATF treats them as a single magazine. Combined weight then drives the distances to buildings, highways, and railways.7eCFR. 27 CFR 555.218 – Table of Distances for Storage of Explosive Materials
Distance rules apply to portable and vehicular magazines the moment they’re parked for stationary storage. Local zoning may add setbacks on top of the federal minimum, so check both before choosing a site.
Housekeeping and Handling Inside the Magazine
Explosives can’t rest directly against interior walls, and they have to be arranged so air can circulate. Nonsparking lattice or similar material can keep containers off the walls. Every container should face so markings are visible, and stock should be organized for easy counting during an inspection.8Bureau of Alcohol, Tobacco, Firearms and Explosives. 27 CFR Part 555 – Quantity and Storage Restrictions
Smoking, matches, open flames, and anything that produces sparks are prohibited inside any magazine, within 50 feet of any outdoor magazine, and inside any room containing an indoor magazine. Tools used to open or close containers must be nonsparking. Metal slitters are allowed only for fiberboard containers, and wood containers should be opened with a wood wedge and a rubber or wooden mallet.
Magazines have to be kept clean, dry, and free of grit, empty packaging, and rubbish. Floors stained by leaking explosive materials need to be cleaned according to the manufacturer’s instructions, and deteriorated explosives destroyed per manufacturer guidance. Clear the surrounding area of rubbish, brush, dry grass, and trees (other than live trees taller than 10 feet) for at least 25 feet in every direction.
The License or Permit You Need First
You can’t legally store explosive materials without a federal explosives license (FEL) or permit from ATF. Fees depend on the activity:
- Manufacturer, importer, or dealer license: $200 for an initial three-year license, $100 to renew
- User permit: $100 for three years, $50 to renew
- User-limited permit (nonrenewable): $75
- Limited permit: $25 for one year, $12 to renew
Every responsible person on the application, meaning anyone with authority to direct the company’s handling of explosive materials, must submit fingerprints on an FD-258 card, a recent color photograph, and a detailed personal questionnaire covering residential history, employment, and criminal background. ATF’s background check covers criminal records, military records, and mental health adjudications. Disqualifying factors include felony indictments, fugitive status, unlawful drug use (including marijuana), dishonorable military discharge, and renunciation of U.S. citizenship.10Bureau of Alcohol, Tobacco, Firearms and Explosives. ATF Form 5400.13A/5400.16 – Explosives Responsible Person Questionnaire
Records, Inventory, and Reporting
You have to maintain a daily summary of magazine transactions for each magazine. Update it by the close of the next business day, and record the manufacturer or brand name, total quantity received that day, total quantity removed, and total remaining on hand at day’s end.11Bureau of Alcohol, Tobacco, Firearms and Explosives. 27 CFR 555.127 – Daily Summary of Magazine Transactions Records can be kept at each magazine or centralized at the business location, but a centralized system still has to maintain separate transaction records for each magazine.
Complete at least one physical inventory of all explosive materials on hand each calendar year, unless a special inventory (required when starting a business, changing locations, or closing) was already taken that year. Display fireworks can be recorded by the number and size of individual items or by packaged display segments, but you must be able to break that down for an inspector on request.12Bureau of Alcohol, Tobacco, Firearms and Explosives. Federal Explosives Law and Regulations Records stay on the business premises for five years from the transaction date, or until the business closes, whichever comes first.13eCFR. 27 CFR Part 555 Subpart G – Records and Reports
If any explosive materials go missing or are stolen, you have 24 hours to report the loss. Licensees and permittees call ATF at 1-800-461-8841 and submit ATF Form 5400.5. Other individuals call the same number and send a written report to the nearest ATF office. Local authorities must be notified as well.14eCFR. 27 CFR 555.30 – Reporting Theft or Loss of Explosive Materials Any inventory discrepancy suggesting theft triggers the same reporting duty.
Separately, anyone storing explosive materials must notify the local fire authority of the type of materials, the magazine capacity, and the location of each storage site. Notify orally before the end of the day storage begins, then send written confirmation within 48 hours.15eCFR. 27 CFR 555.201 – General
What Noncompliance Costs
Federal explosives violations under 18 U.S.C. ยง 844 carry prison sentences of up to ten years.16Office of the Law Revision Counsel. 18 USC 844 – Penalties Under the general federal sentencing statute, individual fines can reach $250,000 for a felony conviction.17Office of the Law Revision Counsel. 18 USC 3571 – Sentence of Fine ATF can also revoke or deny your federal explosives license, ending your ability to legally possess, store, or transfer explosive materials. Storage violations and record-keeping failures are common triggers, and they tend to compound: a magazine built out of spec that also lacks daily transaction records will draw a harsher response than either problem alone.