Shotgun shells are made of plastic because it outperforms every other material at the job: sealing explosive gases, resisting moisture, protecting the shot payload, and doing all of this cheaply enough for mass production. The shift from paper to plastic happened in the early 1960s, and the reasons were so compelling that plastic became the universal standard within a couple of decades.
What Plastic Replaced
Before plastic, shotgun shells used paper hulls and fiber wads made from cardboard or other plant-based materials. These worked, but they had a serious weakness: water. Paper hulls absorbed moisture even through their wax coatings, causing them to swell. A swollen shell could jam in the chamber, fail to feed in a semi-automatic shotgun, or produce inconsistent pressures when fired. For hunters caught in rain, wading through marshes after waterfowl, or storing ammunition in humid conditions, paper shells were unreliable at exactly the moments reliability mattered most.
Remington began producing plastic shotgun shells around 1960, and by the mid-1960s the transition was well underway across the industry. The wax coating on paper hulls was water-resistant but not waterproof. Plastic simply eliminated the problem.
Why Polyethylene Works So Well
The specific plastic used in most shotgun shells is polyethylene, the same family of polymers found in milk jugs and plastic bags. Despite being the simplest polymer by molecular structure, polyethylene has a rare combination of traits that make it nearly ideal for ammunition.
When a shotgun fires, the propellant ignites and generates enormous pressure inside the chamber. A standard 12-gauge shell must handle up to 11,500 PSI, and magnum 3.5-inch loads push that to 14,000 PSI. The temperatures spike alongside the pressure. Polyethylene holds up under these extreme conditions without meaningful changes to its structure. Studies comparing fired and unfired plastic components have confirmed that the combustion process doesn’t appreciably alter the polymer, meaning the material performs consistently shot after shot and shell after shell.
Polyethylene is also thermoformable, which means it can be heated and molded into virtually any shape. This matters because a shotgun shell isn’t just a tube. The plastic hull, the wad (the cup that holds the pellets), and the gas seal at the base all have specific geometries designed to control how the shell performs. Manufacturers can fine-tune wall thickness, flexibility, and internal dimensions with precision that paper never allowed.
How Plastic Seals the Chamber
One of the most important jobs of a shotgun shell is containing the expanding gases behind the shot charge so that all that energy pushes the payload forward rather than leaking backward. In any firearm that uses cased ammunition, the case itself provides this seal by expanding slightly under gas pressure, pressing outward against the chamber walls. Plastic does this reliably because it has just enough flexibility to deform under pressure and then spring back, allowing the spent hull to eject cleanly.
The plastic wad inside the shell serves a related purpose. It sits between the powder charge and the pellets, acting as a piston and a protective cup simultaneously. When the powder ignites, the wad prevents hot gases from blowing through the shot column, which would scatter the pellets unevenly. It also cushions the pellets from the initial acceleration force, reducing deformation that would hurt accuracy. Fiber wads did this adequately, but plastic wads do it with far greater consistency because they can be molded to exact tolerances.
Cost and Reloading Advantages
Plastic shells are cheaper to manufacture than paper. The raw material costs less, the molding process is faster, and the finished product requires no wax treatment or special moisture-proofing steps. For an item that recreational shooters might go through by the hundreds in a single afternoon of clay shooting, cost per shell matters.
Plastic hulls also hold up better for reloading. Many shooters reload their spent shells with fresh primers, powder, wads, and shot to save money. A plastic hull can typically survive several reload cycles before the mouth starts to split or the base weakens. Paper hulls degraded faster with each firing and reloading, limiting their useful life.
The Environmental Tradeoff
The same durability that makes plastic shells effective creates an environmental problem. Plastic wads fired over open water or fields don’t biodegrade. They wash up on beaches, accumulate in wetlands, and persist in the environment for decades. Oregon Sea Grant has documented plastic wads as a recurring type of shoreline debris, distinct enough to be used in educational programs about marine pollution.
The old fiber wads broke down naturally. The shift to plastic traded one problem (unreliable ammunition) for another (persistent pollution), and the shooting industry is only now starting to grapple with it. Several companies are developing wads made from biodegradable materials that mimic the performance of polyethylene without the permanence. Some manufacturers have also revisited paper hulls with improved moisture barriers, though these remain niche products. The challenge is matching plastic’s performance and price point with materials that actually decompose, and so far no biodegradable option has achieved widespread adoption.
For now, plastic dominates because nothing else combines moisture resistance, pressure tolerance, moldability, gas sealing, reloadability, and low cost in a single material. Every alternative involves a compromise that most shooters and manufacturers haven’t been willing to accept.