SHOTGUN SHELLS
12, 20 and .410 bore, sport and security
Shotgun shells are supplied in 12 gauge, 20 gauge and .410 bore for sport shooting, security and law enforcement duties. Loadings run from fine birdshot for clay and upland use through buckshot for close-quarters security work to rifled slugs for solid-projectile applications. The 12 gauge is by far the most widely used size; the 20 gauge is favoured for upland game and the .410 is the smallest bore in common production.
Full Specifications
Shell dimensions
| Designation | 12 gauge / 12 bore; metric 12/70, 12/76, 12/89 by shell length |
|---|---|
| Case type | Rimmed straight-walled plastic or paper tube on a metallic base |
| Bore diameter, 12 gauge | 18.5 mm (0.729 in) nominal |
| Bore diameter, 20 gauge | 15.6 mm (0.615 in) |
| Bore diameter, .410 | 10.4 mm (0.410 in) — a true bore size |
| Shell lengths, 12 gauge | 70 mm (2¾ in), 76 mm (3 in), 89 mm (3½ in) |
| Shell lengths, 20 gauge | 64, 70, 76 and 89 mm |
| Shell lengths, .410 bore | 51, 64 and 76 mm |
| Equivalent ball weight, 12 ga | 37.80 g (1.333 oz) of pure lead |
Loadings and ballistics
| 12 ga 2¾ in reference | 1⅛ oz payload at 1,330 ft/s |
|---|---|
| 12 ga 3 in reference | 1¼ oz at 1,375 ft/s |
| 12 ga 3½ in reference | 2¼ oz at 1,150 ft/s |
| 20 ga 2¾ in reference | 1 oz at 1,220 ft/s |
| .410 bore 3 in reference | 11/16 oz at 1,135 ft/s |
| 00 buckshot | 8.38 mm (0.330 in) pellets; 8–18 pellets per shell by length |
| Birdshot pellet counts | #6 = 225/oz, #7½ = 350/oz, #8 = 410/oz, #9 = 585/oz |
| Rifled slug | Approx. 28 g (432 gr) at around 500 m/s |
Standards & pressure
| SAAMI MAP, 12 gauge | 11,500 psi (2¾ and 3 in); 14,000 psi for 3½ in |
|---|---|
| SAAMI MAP, 20 gauge | 12,000 psi |
| SAAMI MAP, .410 bore | 12,500 psi (2½ in); 13,500 psi (3 in) |
| Governing standards | C.I.P.; SAAMI Z299.2–2019; UK proof house rules |
| Primer | Large shotgun primer containing both priming charge and anvil |
Service context
| Effective range | 18 m cylinder to 37 m full choke with buckshot; 100 m+ with rifled slugs |
|---|---|
| Typical platforms | Pump-action, semi-automatic and over-under shotguns |
| Applications | Clay and field sport, security and law enforcement, less-lethal munitions |
Dimensional, ballistic and pressure figures are the published C.I.P., NATO and SAAMI reference values for the shotgun shell cartridge (reference data; SAAMI shotshell reference ammunition table). Steadfast production lots are proof tested and certified against the applicable standard. Product imagery is an in-house Steadfast studio visualisation and is indicative only; actual finish, headstamp and lot markings follow the applicable standard and the customer order.
