Designing a Caliber-Specific Ammo Storage System (How It Works)

We didn’t want to build “another ammo box.”

We wanted to build a standardized storage system that worked across calibers and matched how hunters and shooters store, transport, and use their ammunition in the real world.

Because if something is going to live in a truck and handle the outdoors, it has to be built properly.

Built for Extreme Conditions

We’re based in Manitoba — one of the few places where temperatures can swing from -40°C in the winter to +40°C in the summer.

We knew we needed to build ammo boxes that could handle both. No worries about freezing in winter, no concerns about warping in summer heat — and something that could take rain, snow, and real outdoor use.

Why We Chose PETG

Material choice mattered from the beginning.

We chose high-impact PETG for our ammo boxes because it’s tough, durable, and offers excellent resistance to water, UV exposure, and extreme temperatures (-40°C to 70°C). This makes it an ideal material for outdoor use in all seasons.

We weren’t interested in making something disposable. We wanted a material that could replace cardboard boxes permanently and hold up for years of hunting and shooting.

With that foundation in place, we turned our focus to the design itself.

A Standardized Ammo Storage System

From the beginning, the goal wasn’t to design a single ammo box.
We wanted to build a standardized storage system that could work across rifle, rimfire, and shotgun ammunition while maintaining consistent exterior dimensions.

The challenge was simple to describe but complex to execute: create one consistent box format that could be adapted across multiple calibers and uses without compromising strength, fit, or usability.

It meant starting from scratch. Every measurement, capacity, and layout had to be considered so the system would store cleanly, transport easily, and make sense whether it was sitting on a shelf, in a vehicle, or heading into the field.

Using the same exterior box dimensions, we designed the system to fit:

• 25 shotgun shells (2¾″ / 3″ / 3½″)
• 40 rifle rounds for common calibers
• Rimfire cases inside a bulk box for modular storage

The goal was to build a modular system that stores cleanly and gives you options — bringing a full box, individual cases, or whatever makes sense for the day.

Designing the Box From the Ground Up

Once the overall system and exterior dimensions were established, the next step was designing the box itself. Every detail had to serve a purpose — strength, usability, and durability in real-world conditions.

We knew early on that we wanted a proper latch instead of a sliding lid. Sliding tops can separate into two pieces and become inconvenient to line up and reassemble. We wanted a box that stays together, opens easily, and feels secure in use.

Each box is assembled with screws for long-term strength and serviceability, and the overall shape takes cues from traditional ammo cans — simple, practical, and built to look at home with the rest of your gear. The exterior ridges also allow us to develop mounts and storage solutions as the system expands.

Shotgun: Setting the Standard Dimensions

The foundation of the system starts with 12-gauge shotgun shells.

We designed the box to hold 25 shells while keeping them easy to remove and handle. From there, the interior was refined to accommodate 2¾″, 3″, and 3½″ shells within the same exterior dimensions.

Once that layout was finalized, it established the standard footprint for the entire East Ridge system. Those same exterior dimensions now carry across rifle and rimfire storage, allowing everything to store cleanly together while serving different purposes.

Rifle Boxes: Built Around the Shoulder, Not the Tip

Rifle ammo is where the details matter most.
Many “one-size-fits-many” boxes use square slots, but a round cartridge has never felt quite right sitting in a square hole.

We don’t rely on generic dimensions. Every rifle caliber is measured, designed, and tested using a fired casing.

Why a fired casing?
Because brass expands slightly when fired and expansion varies by caliber. Designing from a fired casing ensures each box can securely fit fired brass, reloaded rounds (neck or full-length resized), and factory ammunition.

We measure:

• neck
• shoulder
• body
• overall length

We then design the internal geometry so cartridges rest on the shoulder of the case, not the bullet tip. Supporting the cartridge on the shoulder eliminates the movement common with tip-up designs, where tapered rounds can shift during transport. It keeps rounds positioned consistently and ensures bullet tips remain free-floating without pressure or contact.

We build in tolerance for short tips, long tips, and variations in seating depth. Our designs account for that with clearance so everything fits the way it should.

Once the initial dimensions are designed, we print a single round cylinder with a viewing port to test fitment. We insert a fired casing and a full cartridge to confirm tolerances and make adjustments if needed.

When that single cylinder fits correctly, we lock in the final dimensions and scale it into the full ammo box layout.

Most rifle boxes hold 40 rounds, covering common hunting calibers from .22-250 up through .300 Win Mag.
For small, high-volume calibers like .223, we designed a version that holds 60 rounds.
For very large cartridges, capacity may drop (around 28 rounds) simply because there’s only so much space—without compromising strength or function.

Rimfire: Modular Cases That Lock Into the System

Rimfire shooters often buy ammunition in bulk, and factory cardboard packaging doesn’t hold up well over time.

It also doesn’t provide a convenient way to bring smaller volumes of ammo hunting, to the range, or along in a side-by-side or ATV.

Our solution was modular. We designed rimfire cases that fit inside a bulk box, allowing you to store larger quantities cleanly while also being able to grab smaller cases when heading out. Three 80-round cases or two 154-round cases fit within the same standardized exterior dimensions.

Why 80 and 154 rounds?
The 80-round case was designed to hold as much as possible while still remaining compact enough to fit in a pocket and allow three cases to fit inside the bulk box.

The 154-round case is the highest-capacity option that fits inside the bulk box, making it ideal for longer range sessions or target shooting while still working within the modular system.

We designed these cases to be easy to use with gloves and cold hands:

• angled, ribbed hinges for easier removal
• side indents for grip and handling
• a flexible snap-shut latch that stays closed during transport

It’s simple gear, but the small details make a huge difference when you’re actually using it.

Tight Tolerances. Real Testing

Many ammo storage products are either one-size-fits-all or standalone boxes that don’t work together as a system.

We take a different approach.

Every East Ridge box is designed to precise tolerances and built to work as part of a consistent system. Rifle, rimfire, and shotgun boxes all share the same exterior dimensions so they store cleanly together and function as one setup rather than a collection of random containers.

Every new caliber is test-fit during development, and every box is checked during production to ensure it performs the way it was designed.

If something doesn’t meet our standards, it’s redesigned.

The goal isn’t to make something that kind of works.
It’s to build something you can rely on for years.

Why the Boxes Aren’t Stackable (Yet)

People ask about stackability a lot.

Our boxes can sit one on another, but they aren’t “locking stackable” in the way some injection-molded boxes are.

That’s a tradeoff we made intentionally.

With 3D printing, stackable interlocks often force compromises in lid strength and overall look. We prioritized a tougher, cleaner lid and a more professional, consistent finish.

Instead, we’re designing our way around that limitation with mounts:

• wall mounts
• stackable mounts
• shelf-style organizers

So the system becomes even more modular over time—without sacrificing durability or looks.

Built With Feedback From Real Shooters

One of the best parts of building East Ridge has been the community response.

People have sent us:

• caliber requests
• fired casings
• design ideas
• feedback from the field

And we want that to continue.

If you don’t see your caliber yet, or you have an idea that would make the system better, reach out. We build this gear for real hunters and shooters—and the feedback directly influences what we design next.

If you want to see what’s coming next — new calibers, releases, and system expansion — follow the build here.