Proofing
The minimum proof and performance requirements for small arms ammunition of NATO calibres are covered in STANAGs as follows:
- 5.56 mm. STANAG 4172 and NATO Manual of Proof and Inspection AC/225 (LG/3-SG/1) D/8.
- 7.62 mm. STANAG 2310 and NATO Manual of Proof and Inspection AC/225 (LG/3-SG/1) D/9.
- 9 mm. STANAG 4090 and NATO Manual of Proof and Inspection AC/225 (P111-SP1) D/170(REV).
- 12.7 mm. STANAG 4383 and NATO Manual of Proof and Inspection AC/225 (LG/3-SG/1) D/11.
Each weapon and component considered vulnerable to the effects of a rapid change in pressure, for example barrels, breech blocks and bolts, will be tested by firing one dry round at a corrected minimum of 25% over pressure and one oiled round at a corrected minimum of 25% over pressure. 25% over pressure means 25% in excess of the Service Pressure (Pmax). The Service Pressure is defined as the mean pressure generated by the Service Cartridge at a temperature of 21°C. Such a high pressure proof is conducted with both the weapon and ammunition conditioned to an ambient temperature of 21°C.
Each weapon will be individually tested, from an ammunition lot that produces a minimum corrected mean chamber pressure in accordance with the table below:
| Calibre | Specific Weapon Detail | Service Pressure Pmax MPa / (psi) |
Proof Round Pressure Requirement MPa / (psi) |
Detailed Requirement for Proof Ammunition |
|---|---|---|---|---|
| 5.56 mm (5.56×45mm NATO) | Designed to chamber NATO ammunition | 430.0 / (62,366) | 537.5 / (77,958) | Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to Commission Internationale Permanente pour l’épreuve des Armes á Feu Portatives (C.I.P.) requirements |
| 7.62 mm (7.62×51mm NATO) | Designed to chamber NATO ammunition | 415.0 / (60,190) | 519.0 / (75,275) | Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to C.I.P. requirements |
| 9 mm (9×19mm NATO) | Designed to chamber NATO ammunition | 252.0 / (36,550) | 315.0 / (45,687) | Pressure recorded in C.I.P. design barrel at mid case position |
| 12.7 mm (12.7×99mm NATO) | Designed to chamber NATO ammunition | 417.0 / (60,481) | 521.3 / (75,608) | Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to C.I.P. requirements |
| All other small arms ammunition for use in "non-NATO Chamber" weapons | As defined by the current C.I.P. legislation. | As defined by the current C.I.P. legislation. |
The above proof round pressure requirements for the 9 mm and 12.7 mm rounds established by the British Ministry of Defence are higher than the current (2008) C.I.P. proof round pressure requirement legislation for the civilian equivalent 9mm Parabellum (C.I.P. Pmax rating 235 MPA / (34,083 psi) and .50 Browning (C.I.P. Pmax rating 370 MPA / (53,663 psi) rounds. The 9x19mm NATO round can be regarded as overpressure ammunition
Read more about this topic: NATO EPVAT Testing