Proof test
Encyclopedia
A proof test is a test wherein a deliberately over-pressured round
is fired from a firearm
in order to verify that the firearm is not defective and will not explode on firing. The firearm is inspected after the test, and if it is found to be in sound condition, then it is marked with a proof mark to indicate that it has been proofed (not proven). In many jurisdiction
s a proof test and valid proof mark are required for the sale of firearms.
A proof round is an ammunition assembly designed to be used in proof testing; this can use a fixed cartridge
, a semi-fixed cartridge, or separately loaded projectile, charge and primer. A proof shot is a special projectile used in a proof round or other projectile weapons, electromagnetic guns
for example. Small arms proof rounds resemble normal cartridges, though they will typically bear special markings to prevent them from being confused for standard cartridges. Large calibre arms, such as artillery
, will in general use an inert solid projectile (the proof shot); although water, sand or iron (powder) filled versions can be found for testing recoil systems.
s or other multi-chamber firearms, each chamber must be proof tested before the firearm may be marked. Examination of the firearm may be as simple as visually inspecting it (defective components may fail in a spectacular manner, resulting in an explosion of the firearm) or may involve more in-depth examination, at the option of the tester.
Because proof testing may or may not result in the destruction of the test specimen, it falls on the border between destructive testing
and nondestructive testing
.
that makes an impression in the metal. Since proof marks are unique and nearly universal, they are often used to identify the origins of firearms that lack normal manufacturer's markings, such as military weapons, which are often produced by large numbers of different manufacturers.
for most commercial cartridges or NATO EPVAT testing
for appropriate military cartridges.
An example proofing round for the 0.5" Browning HMG (12.7 x 99 mm) is the 'Cartridge, Calibre, .50, Test, High Pressure, M1'. This uses the standard weight 0.5" M1 round propellant (240 grs of WC860), but a bullet weighing 999 grs (+/- 11 grs). The M1 proof round gives a proofing pressure of ~65,000 psi, 11,000 psi (~17%) above the standard service pressure.
member states every civil firearm has to be professionally proofed in accredited Proof Houses before it can be sold to consumers.
The standard proof test consist of firing two overloaded cartridges that produce 25% more chamber pressure then the C.I.P. specified maximum pressure limit for the same cartridge in its commercial version. The standard proof of pistol, revolver and rimfire cartridges is performed with overloaded cartridges that produce 30% more chamber pressure than the C.I.P maximum pressure limit for the same cartridge in its commercial version. There are only two overloaded firings to avoid excessive stress to the arm, especially the barrel which is the main part suffering this overload beside the chamber (when not part of the barrel) and the locking mechanism. After the test, the arm is disassembled by the proof house technicians for nondestructive testing
looking for Magnetic flux leakage
through fluoroscopic lamp in a dark room. Many manufacturers, including Glock Ges.m.b.H., package the casings from a firearm's proof ammunition in a sealed envelope accompanying the firearm so that authorities in C.I.P.-signatory states and civilian purchasers in other countries can conduct an independent examination if they desire.
Before the year 2006 the standard test consisted of firing two overloaded cartridges producing 30% more chamber pressure then the C.I.P. specified maximum chamber gas pressure limit for the same cartridge in its commercial version.
Voluntarily testing beyond the current legally required standard test benchmark is often also possible for consumers who intend the use their firearms under extreme conditions (hot climates, long strings of shots, etc.). In case a firearm passes such a proof-test a pass mark termed superior proof mark is stamped in every successfully tested firearm.
Under C.I.P. proof test standards a drilled case is used and the piezo measuring device (transducer) will be positioned at a distance of 25 mm from the breech face when the length of the cartridge case permits that, including limits. When the length of the cartridge case is too short, pressure measurement will take place at a cartridge specific defined shorter distance from the breech face depending on the dimensions of the case.
The difference in the location of the pressure measurement gives different results than the C.I.P. standard.
the same as the shot they are emulating. Crack analysis is often undertaken on large-caliber weapons after testing has been carried out.
The proof shot is normally a high-drag projectile since its job is over once it has left the muzzle of the gun. A high-drag projectile is advantageous for two reasons; first, it reduces the impact velocity when fired against an earth or sand backstop, and second, it reduces the range if no backstop is used. Excessive range can be a very problematic when firing any large-caliber round; safety traces can often exceed the bylaw areas of the firing range, so range reduction is imperative. This is even more of a problem when high velocity, low drag rounds such as APDS
or APFSDS are used.
Although proof shots are used in the service proof of barrels before use, the vast majority are used in propellant charge design. Proof shot emulating APFSDS rounds are also used in stabilizing-fin SoD trials, which is often combined with a charge design trial.
electric gauges and velocity by Doppler radar
(in-bore or aeroballistic), or photocell counter chronograph
s. In addition strain and temperature
readings may also be recorded. If required, high speed photography (synchroballistic photography, high speed digital stills, head on cine, or flight follower) may also be used.
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
is fired from a firearm
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
in order to verify that the firearm is not defective and will not explode on firing. The firearm is inspected after the test, and if it is found to be in sound condition, then it is marked with a proof mark to indicate that it has been proofed (not proven). In many jurisdiction
Jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...
s a proof test and valid proof mark are required for the sale of firearms.
A proof round is an ammunition assembly designed to be used in proof testing; this can use a fixed cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
, a semi-fixed cartridge, or separately loaded projectile, charge and primer. A proof shot is a special projectile used in a proof round or other projectile weapons, electromagnetic guns
Railgun
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...
for example. Small arms proof rounds resemble normal cartridges, though they will typically bear special markings to prevent them from being confused for standard cartridges. Large calibre arms, such as artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...
, will in general use an inert solid projectile (the proof shot); although water, sand or iron (powder) filled versions can be found for testing recoil systems.
Testing methodology
For both small arms and heavy weapons, the gun is fired remotely and then examined; if undamaged, it is assumed to be safe for normal use and a proof mark is added to the barrel. In the case of revolverRevolver
A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...
s or other multi-chamber firearms, each chamber must be proof tested before the firearm may be marked. Examination of the firearm may be as simple as visually inspecting it (defective components may fail in a spectacular manner, resulting in an explosion of the firearm) or may involve more in-depth examination, at the option of the tester.
Because proof testing may or may not result in the destruction of the test specimen, it falls on the border between destructive testing
Destructive testing
In destructive testing, tests are carried out to the specimen's failure, in order to understand a specimen's structural performance or material behaviour under different loads...
and nondestructive testing
Nondestructive testing
Nondestructive testing or Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage....
.
Proof marks
A proof mark is a mark specific to the manufacturer, importer, or testing facility that is performing the test. It generally takes the form of a stampStamping (metalworking)
Stamping includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining. This could be a single stage operation where every stroke of the press produce the desired form on the sheet...
that makes an impression in the metal. Since proof marks are unique and nearly universal, they are often used to identify the origins of firearms that lack normal manufacturer's markings, such as military weapons, which are often produced by large numbers of different manufacturers.
Small arms proof testing
A small arms proof round is loaded to a higher than normal service pressure, stressing both the gun barrel and breech during firing. This can be due to a heavy projectile fired using the standard propelling charge, the standard projectile fired with a different propellant type or weight, or combinations of charge and bullet weight to give the required proofing pressure. Minimum proof testing pressures are specified by the owner of the cartridge specification, such as C.I.P. or SAAMISaami
Saami or SAAMI can stand for:*Sami people*Sami languages*Sporting Arms and Ammunition Manufacturers' Institute...
for most commercial cartridges or NATO EPVAT testing
NATO EPVAT testing
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....
for appropriate military cartridges.
An example proofing round for the 0.5" Browning HMG (12.7 x 99 mm) is the 'Cartridge, Calibre, .50, Test, High Pressure, M1'. This uses the standard weight 0.5" M1 round propellant (240 grs of WC860), but a bullet weighing 999 grs (+/- 11 grs). The M1 proof round gives a proofing pressure of ~65,000 psi, 11,000 psi (~17%) above the standard service pressure.
Proof testing in C.I.P. regulated countries
In C.I.P.Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives is an international organisation whose members are 14 states, mainly European....
member states every civil firearm has to be professionally proofed in accredited Proof Houses before it can be sold to consumers.
The standard proof test consist of firing two overloaded cartridges that produce 25% more chamber pressure then the C.I.P. specified maximum pressure limit for the same cartridge in its commercial version. The standard proof of pistol, revolver and rimfire cartridges is performed with overloaded cartridges that produce 30% more chamber pressure than the C.I.P maximum pressure limit for the same cartridge in its commercial version. There are only two overloaded firings to avoid excessive stress to the arm, especially the barrel which is the main part suffering this overload beside the chamber (when not part of the barrel) and the locking mechanism. After the test, the arm is disassembled by the proof house technicians for nondestructive testing
Nondestructive testing
Nondestructive testing or Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage....
looking for Magnetic flux leakage
Magnetic flux leakage
Magnetic flux leakage is a magnetic method of nondestructive testing that is used to detect corrosion and pitting in steel structures, most commonly pipelines and storage tanks. The basic principle is that a powerful magnet is used to magnetize the steel. At areas where there is corrosion or...
through fluoroscopic lamp in a dark room. Many manufacturers, including Glock Ges.m.b.H., package the casings from a firearm's proof ammunition in a sealed envelope accompanying the firearm so that authorities in C.I.P.-signatory states and civilian purchasers in other countries can conduct an independent examination if they desire.
Before the year 2006 the standard test consisted of firing two overloaded cartridges producing 30% more chamber pressure then the C.I.P. specified maximum chamber gas pressure limit for the same cartridge in its commercial version.
Voluntarily testing beyond the current legally required standard test benchmark is often also possible for consumers who intend the use their firearms under extreme conditions (hot climates, long strings of shots, etc.). In case a firearm passes such a proof-test a pass mark termed superior proof mark is stamped in every successfully tested firearm.
Proof test differences
Under SAAMI proof test procedures, for bottlenecked cases the centre of the transducer is located .175" behind the shoulder of the case for large diameter (.250") transducers and .150" for small diameter (.194") transducers. For straight cases the centre of the transducer is located one-half of the transducer diameter plus .005" behind the base of the seated bullet. Small transducers are used when the case diameter at the point of measurement is less than .35".Under C.I.P. proof test standards a drilled case is used and the piezo measuring device (transducer) will be positioned at a distance of 25 mm from the breech face when the length of the cartridge case permits that, including limits. When the length of the cartridge case is too short, pressure measurement will take place at a cartridge specific defined shorter distance from the breech face depending on the dimensions of the case.
The difference in the location of the pressure measurement gives different results than the C.I.P. standard.
Large caliber proof testing
The test of a large-caliber weapon system primarily covers the strength of the barrel, breech and recoil systems. The proof shot has to resemble the resistance to motion (bore/rifling friction, shot start pressures, etc) and profile to the propellant gases that the actual service projectile will give. For this reason, proof shots for APFSDS rounds have fin units and all must have profiles behind the obturatorObturator
Obturator may refer to:In medicine:* Obturator artery* Obturator nerve* Obturator vein* Obturator externus muscle* Obturator internus muscle* Obturator membrane* Obturator canal* Obturator foramen...
the same as the shot they are emulating. Crack analysis is often undertaken on large-caliber weapons after testing has been carried out.
The proof shot is normally a high-drag projectile since its job is over once it has left the muzzle of the gun. A high-drag projectile is advantageous for two reasons; first, it reduces the impact velocity when fired against an earth or sand backstop, and second, it reduces the range if no backstop is used. Excessive range can be a very problematic when firing any large-caliber round; safety traces can often exceed the bylaw areas of the firing range, so range reduction is imperative. This is even more of a problem when high velocity, low drag rounds such as APDS
APDS
APDS may refer to:*Armour-piercing discarding sabot*Androgynous Peripheral Docking System*Augusta Preparatory Day School...
or APFSDS are used.
Although proof shots are used in the service proof of barrels before use, the vast majority are used in propellant charge design. Proof shot emulating APFSDS rounds are also used in stabilizing-fin SoD trials, which is often combined with a charge design trial.
Instrumentation used in Proofing
When running a charge development, or Strength of Design (SoD) trial, the charge mass and service pressure will gradually be worked up to the required proofing pressure of the weapon system. Readings will be taken of chamber pressure by copper crusher, or piezoPiezo
"Piezo", derived from the Greek piezein, which means to squeeze or press, is a prefix used in:* Piezoelectricity* Piezoresistive effect* Piezometer* Piezo ignition* Piezoelectric sensor* Piezoelectric loudspeakers* Piezo Audio Amplifier...
electric gauges and velocity by Doppler radar
Doppler radar
A Doppler radar is a specialized radar that makes use of the Doppler effect to produce velocity data about objects at a distance. It does this by beaming a microwave signal towards a desired target and listening for its reflection, then analyzing how the frequency of the returned signal has been...
(in-bore or aeroballistic), or photocell counter chronograph
Gun chronograph
A gun chronograph is an instrument used to measure the velocity of a projectile fired by a gun.-History:Around 1800, the ballistic pendulum was used to measure the momentum of the projectile fired by a gun; dividing the momentum by the projectile mass gives the velocity.An early chronograph that...
s. In addition strain and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
readings may also be recorded. If required, high speed photography (synchroballistic photography, high speed digital stills, head on cine, or flight follower) may also be used.