Why the names are confusing
A ".50 cal ammo can" doesn't mean it holds .50 BMG for you. The names come from US military designations for cans originally used to pack linked machine-gun ammunition. Civilians kept the names because they're a handy shorthand for size.
Today you'll see three kinds of cans on the market:
- Military-style steel cans, new or surplus, using the original designations like M19A1 and M2A1.
- Plastic cans from makers like MTM, often named by the military size they resemble, such as "50 Cal" or "Tall 30 Cal."
- Specialty sizes like the Fat 50 or large 20mm cans.
The common sizes
| Name | Common designation | Shape | Good for |
|---|---|---|---|
| .30 cal | M19A1 | Small, narrow | Handgun ammo boxes, a range day's worth, small parts |
| .50 cal | M2A1 | Taller and wider than .30 cal | The all-rounder: handgun or rifle boxes, mixed storage |
| Fat 50 | Varies by maker | Same general length as .50 cal, noticeably wider | Bulky shotshell boxes, larger rifle boxes |
| 20mm | Often listed as M548 | Large and heavy | Bulk storage, gear; can get very heavy when full |
Exact dimensions vary a little between makers and between surplus and new production. If fit matters, check the specific listing before you buy.
How much fits?
This is the question everyone asks, and the honest answer is: it depends on the boxes. A can that holds a certain number of 9mm boxes might hold a very different number of .223 boxes or shotshell boxes. Round counts quoted online assume a particular box size and packing method.
Some practical rules:
- Keep ammo in its original boxes. It takes more space than loose rounds, but it protects the cartridges and preserves the lot number and load information.
- Test-fit with your actual boxes before buying a stack of identical cans.
- Watch the weight. A fully packed .50 cal or 20mm can of rifle ammo is heavy. Make sure you can lift it safely and that your shelf can hold it.
- Consider buying pre-packed. Retailers sell ammo already packed in cans. Ammunition Depot's ammo can combos list the round count with the can.
Our ammo can vs battle pack vs case guide compares packaging options.
Metal vs plastic
| Steel | Plastic (polypropylene) | |
|---|---|---|
| Durability | Very tough; dents but rarely breaks | Tough, but can crack under heavy impact |
| Weight | Heavier when empty | Lighter |
| Rust | Can rust if paint is damaged | Doesn't rust |
| Seal | Rubber gasket on most designs | Many have an O-ring or gasket |
| Stacking | Stacks well | Many designs are made to stack |
| Cost | Surplus can be budget; new varies | Usually budget to mid-range |
Both work well for most people. Steel is the classic choice for heavy, long-term storage. Plastic is lighter and easier to carry to the range. Ammunition Depot lists both styles, including M19A1 and M2A1 steel cans and MTM Case-Gard plastic cans, on its ammo cans page.
Check the gasket
A can's seal depends on its gasket, and gaskets age. Before you trust a can, especially a surplus one:
- Open the lid and look at the rubber gasket. It should be soft, unbroken and seated in its channel.
- Close the lid and latch it. It should close snugly, with some resistance.
- Look for rust, dents or bent edges around the lid that could stop a full seal.
- Replace the can, or the gasket where possible, if the rubber is cracked or flattened.
Remember that a sealed can traps whatever air was inside when you closed it. Close it in a dry room, not a humid garage, and add a desiccant pack. Our guide to ammo storage, humidity and heat covers why.
Label everything
A wall of identical green cans is useless if you don't know what's inside. Label the outside of each can with:
- Caliber or gauge.
- Load (bullet weight and type, or shot size).
- Round count.
- Date packed, and lot number if you keep track.
Keep calibers separated by can whenever you can. A can holding mixed calibers is how dangerous mix-ups happen. Our ammo labels and inventory guide has a simple system.
Which size should you buy?
- One or two handgun calibers, modest quantities: a few .30 cal cans.
- A general mix of rifle and handgun ammo: .50 cal cans, the most versatile size.
- Shotshells: Fat 50 cans fit bulky boxes better.
- Bulk storage you won't move often: 20mm cans, if your back and shelves can handle the weight.
- Range trips: a lighter plastic can with a handle.
Where to keep the cans
A great can in a bad spot still lets ammo down. Placement matters as much as the container.
- Inside, not out. A closet or interior room in your home usually has more stable temperature and humidity than a garage, attic or shed.
- Off the floor. Concrete floors can wick moisture and get cold, which encourages condensation. Use a shelf or a pallet.
- Away from chemicals. Solvents, oils and cleaning products can harm ammunition. Keep them on a different shelf.
- Secured. Store ammunition out of reach of children and unauthorized users. Many owners keep it in a locked cabinet or room.
- Weight-rated. Full cans are heavy. Check the load rating of shelves before stacking.
Desiccant tips
Silica gel packs are the most common desiccant for ammo cans. Some change color as they absorb moisture, which makes checking easy. Follow the desiccant maker's instructions for how many to use and how to dry or replace them. Check them a few times a year, especially after humid seasons.
Surplus cans
Surplus military cans are popular and often budget-friendly. They may arrive with old markings, scuffs or worn gaskets. Inspect each one, clean out any debris, and replace or reject cans with damaged seals. Some sellers grade surplus cans by condition; read the listing carefully before buying in quantity.
Carrying cans to the range
For range trips, a smaller can with a sturdy handle is easier to carry than a big one packed full. Many shooters keep one .30 cal or small plastic can as a dedicated "range can" with a day's worth of ammo, ear and eye protection, and a few spare magazines. Keep only one caliber in it at a time, or use clearly labeled boxes inside, so nothing gets mixed up at the bench. When you get home, move leftover ammo back into long-term storage instead of leaving it in the car, where heat, cold and theft are all risks.
If you buy ammo already packed in a can, inspect the gasket and latch when it arrives, just as you would with an empty can. It's the same container either way.
Frequently asked questions
What is the difference between a .30 cal and .50 cal ammo can?
The .30 cal (M19A1) is smaller and narrower. The .50 cal (M2A1) is taller and wider and fits more boxes. The names refer to their original military use.
How many rounds fit in a .50 cal ammo can?
It depends on the caliber and boxes. Test-fit your boxes, or buy pre-packed cans that list the round count.
Are plastic ammo cans as good as metal?
For most home storage, yes, if the seal is good. Steel is tougher; plastic is lighter and won't rust.
Are ammo cans airtight?
A good gasket keeps most outside air and moisture out, but don't assume it's perfect. Check gaskets and use desiccant.
What is a Fat 50 ammo can?
A can about as long as a .50 cal can but wider. It's popular for shotshell boxes and bulky items.
Editorial note: This guide is based on manufacturer information, retailer listings and published references. We haven't tested these containers hands-on. Specifications, availability and prices change, so check the current listing before buying. We may earn a commission from links on this page at no extra cost to you.
Affiliate disclosure: Some links on this page are affiliate links to Ammunition Depot. We may earn a commission if you buy through them, at no extra cost to you. Our editorial choices are not influenced by commissions. Check current price, stock and specifications directly with the retailer.