By Luke Dalton | Updated 14 July 2026

In 30 Seconds

An ammo box is a purpose built container for transporting and storing ammunition, and the most recognisable version is the steel M2A1, often called the 50 cal ammo tin. Introduced in the 1950s to carry 100 round belts of .50 calibre ammunition for the M2 Browning machine gun, it is welded steel with an airtight rubber gasket seal, a folding carry handle and a removable lid. Those same qualities, airtight, waterproof, stackable and near indestructible, are why people now use ammo tins for everything from tools and camping kit to keeping coffee fresh.

What an Ammo Box Actually Is

An ammo box, ammo tin, ammo can or ammunition box (the names are used interchangeably) is a sealed container built to military specification for moving ammunition safely. The defining features are a rigid body in steel or plastic, a lid that clamps down onto a rubber gasket to form an airtight and waterproof seal, and a design that stacks securely so boxes can be transported in bulk.

Genuine military ammo boxes are overbuilt by design. They are made to be dropped, stacked under hundreds of kilograms, rained on, and thrown in and out of vehicles for years, and still keep the contents bone dry. That is exactly why surplus ammo tins have a second life as some of the best general purpose storage containers you can buy.

The M2A1: A Short History of the 50 Cal Ammo Box

The steel M2A1 ammunition box was introduced in the 1950s for .50 calibre machine gun ammunition, replacing the earlier M2 pattern. It was designed to hold link belts of 100 cartridges of .50 cal ammunition for the M2 Browning machine gun, though in practice it has carried almost every small and medium calibre round, plus flares, fuses and grenades, according to the history of the M2A1 compiled by PlastPack Outdoor.

The design has barely changed in seventy years because it did not need to. Seam welded steel body, quick release latch, a rubber gasket under the lid making a near waterproof seal, and a metal bar handle that folds flat for stacking or lifts up for carrying. Outside dimensions are roughly 30.5cm long, 15.5cm wide and 19cm tall, and the pattern is defined by the American military specification MIL-DTL-3060.

Genuine tins are painted olive drab or olive green and carry stamped or stencilled markings: the manufacturer, the model, the year of manufacture and sometimes the original contents. Those markings are part of the appeal. Every genuine tin has a service history.

Ammo Box Sizes and Types

The M2A1 is the size most people mean when they say ammo box or ammo tin. The smaller 30 cal box suits glove boxes and day sacks. Plastic versions are lighter and cheaper but give up the fire resistance, crush strength and the look of the steel original. Wooden crates are a different animal altogether, more display piece than working container.

How to Spot a Genuine Ammo Tin

The market is full of replicas, and some are decent, but if you want the real thing, check four points. First, the seal: a genuine tin has a solid rubber gasket running the full perimeter of the lid, and when you close the latch you should feel real resistance as the gasket compresses. Second, the welds: genuine boxes are seam welded with the latch, hinge and handle spot welded to the body. Third, the markings: stamped manufacturer codes, model designation and year. Fourth, the weight: a real M2A1 in heavy gauge steel has serious heft. A thin, light, rattly box with painted on markings is a replica. Replicas are fine for display, but they will not hold a seal, and the seal is the entire point.

Our Genuine M2A1 Ammo Tin skips the surplus lottery entirely. It comes new from the same supplier that provides ammunition boxes to the MOD, in RAL 6031 olive green, so you get the genuine article without the rust, dents and mystery smells that can come with fifty year old surplus.

What People Actually Use Ammo Boxes For

Ask ten ammo tin owners what is in theirs and you will get ten answers. The airtight, waterproof seal makes them ideal for anything that hates moisture: tools, electronics, first aid kits, camera gear, documents, batteries and camping supplies. The crush strength makes them perfect vehicle boxes, thrown in the back of a truck or wagon and forgotten about. The stackable design makes them a garage and workshop storage system. And plenty of people just think they look brilliant on a shelf, which is also a valid use.

Our favourite use, obviously, is coffee. Ground coffee and beans degrade fast when exposed to air and moisture, and an airtight steel tin is about the best domestic coffee storage there is. That is the whole idea behind the Coffee Resupply: four bags of Contact Coffee packed into a genuine M2A1 tin that then becomes your permanent coffee store. If you are into brewing outdoors, the tin doubles as a field kit box, and our guide to camping with coffee covers the rest of the setup.

Ammo Box Projects: Speakers, Stoves and Second Lives

There is a whole culture of ammo box conversion projects, and the M2A1 is the canvas of choice because the steel takes drilling, cutting and welding without complaint. The ammo box speaker is the classic: a Bluetooth amplifier and a pair of drivers mounted through the front face, with the sealed steel body acting as the enclosure. The ammo can stove is the field favourite, with a door cut into one face and a flue in the lid, turning the tin into a compact wood burner for a bothy or a garden. People build ammo box tool kits with foam inserts, ammo box battery banks for camping power, geocache containers, and glove box tidies for Land Rovers and pickups.

Two practical notes if you are converting one. Cutting or drilling the body obviously ends the airtight seal, so decide whether the project needs the box sealed or open before the first hole. And if the tin is genuine surplus rather than new production, give the inside a proper clean first, because half a century of unknown history deserves at least a wipe down. For projects where the seal matters, like a battery bank or dry box, start with a tin whose gasket is intact, and do the mounting through the lid skirt rather than the gasket face.

And if the project is caffeine rather than carpentry, the strongest thing you can put in an ammo tin is the Red On range, the high caffeine end of the Contact Coffee line built for early starts and long nights.

Ammo Boxes and UK Ammunition Storage

One honest note for UK certificate holders, since people ask. If you hold a firearm certificate, the security conditions on your certificate and the Home Office Firearms Security Handbook govern how firearms and ammunition must be stored, and a standalone ammo box on a shelf does not by itself meet those requirements. An ammo tin is a superb container, but for certificated ammunition it belongs inside your approved security arrangements, not instead of them. If in doubt, speak to your local firearms licensing team.

Buying Guide: What to Pay and What to Avoid

Used surplus M2A1 tins in the UK typically run from around £10 to £20 depending on condition, and condition varies wildly. Check the gasket is intact and pliable rather than cracked, check the hinge and latch operate cleanly, and check inside for rust, because a rusty interior undoes the whole point of a sealed box. New production genuine tins cost slightly more and remove the gamble. Avoid anything described as ammo box style, which is retail code for a replica, and be wary of listings without clear photos of the gasket and markings.

If you want new, genuine and stencilled, the Genuine M2A1 Ammo Tin is £22. If you want it arriving full of the strongest coffee in Britain, the Coffee Resupply packs four bags into the tin and saves money against buying everything separately. Not sure which coffee? Start with our guide to the strongest coffee in the world or the coffee strength scale explained.

Frequently Asked Questions

What are ammo boxes called?

Ammo box, ammo tin, ammo can and ammunition box all refer to the same thing: a sealed military container for ammunition. The steel M2A1 is nicknamed the 50 cal box because it was built for .50 calibre belts, and the smaller M19A1 is called the 30 cal.

What is an M2A1 ammo box?

The M2A1 is a steel ammunition box introduced in the 1950s to carry 100 round belts of .50 calibre ammunition for the M2 Browning machine gun. It is seam welded steel with a rubber gasket seal, folding handle and removable lid, and it is the most common ammo tin pattern in the world.

Are ammo boxes worth it?

For storage, yes. A genuine steel ammo tin is airtight, waterproof, crush proof, stackable and lasts decades, for roughly the price of a plastic storage box that does none of those things. Few containers offer the same durability per pound.

Are ammo tins airtight and waterproof?

A genuine M2A1 in good condition is airtight and near waterproof thanks to the rubber gasket that compresses when the lid is latched. Check the gasket on used tins, because a cracked or perished gasket loses the seal.

What size is a 50 cal ammo box?

The M2A1 50 cal ammo box measures roughly 30.5cm long, 15.5cm wide and 19cm tall on the outside, and weighs around 2.5kg empty. It comfortably holds four 227g bags of coffee, a decent tool roll, or a full vehicle first aid kit.

Where can I store ammunition in the UK?

UK firearm certificate holders must store ammunition according to the security conditions on their certificate and Home Office guidance, which normally means secure, approved arrangements that prevent unauthorised access. An ammo box alone does not satisfy those conditions. Check with your local firearms licensing department.

Is it legal to own an ammo box in the UK?

Yes. An ammo box is just a steel container, and owning one requires no licence or paperwork of any kind. The legal controls apply to firearms and ammunition, not to the empty boxes they were once carried in.

Do ammo tins keep coffee fresh?

Yes, and better than most purpose made coffee canisters. Coffee degrades through exposure to air, moisture and light, and a latched M2A1 blocks all three. That is why the Coffee Resupply ships four bags of coffee inside one.

How do I know if an ammo box is genuine?

Check for a full perimeter rubber gasket, seam welded construction, stamped manufacturer and model markings, and real weight in the steel. Light, rattly boxes with printed markings and no gasket are replicas.

Can you paint or customise an ammo tin?

Yes. Steel tins take spray paint and stencils well, and customising them is half the culture. Keep paint away from the gasket and the mating faces of the lid so the seal still compresses properly.

Related Guides

The strongest coffee in the world settles what strength actually means and which coffees genuinely deliver it. The coffee strength scale explained breaks down the numbers on the side of the bag. And camping with coffee covers brewing decent coffee in the field, ammo tin kit box included.

References and Further Reading

History of the M2A1, PlastPack Outdoor: ppd-outdoor.com/pages/history-of-the-m2a1. General overview of the M2 ammo can, Ammunition-Box.com: ammunition-box.com/general-overview-of-the-m2-ammo-can. Firearms Security Handbook 2020, Home Office, GOV.UK: gov.uk/government/publications/firearms-security-handbook.