NATO EPVAT testing

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NATO EPVAT testing is one of the three recognized classes of procedures used in the world to control the safety and quality of firearms ammunition.

Beside this, there are also the SAAMI class of procedures and the C.I.P. class of procedures.

EPVAT Testing is described in unclassified documents by NATO, more precisely by the AC/225 Army Armaments Group (NAAG).^[1]

EPVAT is an abbreviation for "Electronic Pressure Velocity and Action Time". This is a comprehensive procedure for testing ammunition using state-of-the-art instruments and computers. The procedure itself is discribed in NATO document AC/225 (Com. III/SC.1)D/200.

Unlike the C.I.P. procedures aiming only at the user's safety, the NATO procedures for ammunition testing also includes comprehensive functional quality testing in relation with the intended use. That is, not only the soldier's safety is looked at, but also his capacity to incapacitate the enemy. As a result, for every ammunition order by NATO, a complete acceptance approval on both safety and functionality is performed by both NATO and the relevant ammunition manufacturers in a contradictory fashion.

For this, a highly accurate and indisputable protocol has been defined by NATO experts using a system of reference cartridges.^[2]^[3]^[4]

The civilian organisations C.I.P. and SAAMI use less comprehensive test procedures than NATO, but NATO test centres have the advantage that only a few chamberings are in military use. The C.I.P. and SAAMI proof houses must be capable of testing hundreds of different chamberings requiring lots of different test barrels, etc..

1 NATO Reference cartridges system
2 Proofing
3 See also
4 References
5 External links

[edit] NATO Reference cartridges system

In this system, the ammunition manufacturers, in close cooperation with NATO, have set aside a batch (also termed "lot") of ammunition they consider to be of very good quality and representative of ammunition that should be delivered to the armies in the next following years. This batch is maintained at approved NATO test centres and distributed to the manufacturers involved. When a new batch (lot) is delivered, a set of 20 reference cartridges are fired to see how they behave with the local equipment and with the current atmospheric conditions. Results are then compared to the reference values as maintained by the NATO and correctors (delta values) are computed. Then, the current batch (lot) of ammunition is fired and the correctors are applied on the measured value giving a result "comparable" to the reference itself.

This test is performed under normal conditions but also by simulating extreme polar or desert conditions using special cooling equipment and ovens to cool or heat the tested ammunition to the appropriate temperatures.^[5]^[6]

[edit] Proofing

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:^[7]

Corrected Proof Pressure Requirement (Service Pressure (Pmax) + 25%)
Calibre	Specific Weapon Detail	Service Pressure Pmax (Mpa / (psi))	Proof Round Pressure Requirement (Mpa / (psi))	Detailed Requirement for Proof Ammunition
5.56 mm (5.56x45mm NATO)	Designed to chamber NATO ammunition	430 / (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 (7.62x51mm NATO)	Designed to chamber NATO ammunition	415 / (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 (9x19mm NATO)	Designed to chamber NATO ammunition	242 / (35,099)	315.0 / (45,687)	Pressure recorded in C.I.P. design barrel at mid case position
12.7 mm (12.7x99mm NATO)	Designed to chamber NATO ammunition	417 / (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 significantly 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.^[8]