Standards
In the United States, standards related to arms and ammunition are maintained and published by the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI), which publishes standard internal pressures of calibers, formerly measured in copper units of pressure and currently in psi based on piezoelectric instrumentation. Official +P pressures are established by the SAAMI for certain cartridges; in general the +P pressure is approximately 10% higher than the standard pressure (see chart below). SAAMI does not have a +P+ pressure standard, but this indicates a pressure higher than the +P loading. In both cases this is below the pressure of proof test cartridge, which all firearms are required to withstand before they may be sold. Proof pressure are established by the SAAMI, as a percentage of the working pressure, so this places an upper bound on the +P+ pressures of 30–40%. By way of comparison, magnum calibers may be loaded to nearly twice the pressure of the rounds from which they were derived. Overpressure rounds are commonly defensive rounds and are loaded by police and others in need of maximum power in a compact firearm. Accordingly, most overpressure rounds are hollow points or other types of expanding ammunition.
"Higher pressure" is not the same as "high pressure"; +P cartridges are generally loaded to pressures far below those typically found in magnum cartridges. The +P standard is designed so that if a shooter was to accidentally use a +P cartridge in a non-+P-rated firearm, the chance of a one-time explosive failure is minimal as long as the gun was in good physical condition. Repeated firing of +P ammunition in a gun not rated for it will drastically speed mechanical failure of the gun, however, and so it should only be used in firearms designated by the manufacturer as safe for +P use.
Read more about this topic: Overpressure Ammunition
Famous quotes containing the word standards:
“Today so much rebellion is aimless and demoralizing precisely because children have no values to challenge. Teenage rebellion is a testing process in which young people try out various values in order to make them their own. But during those years of trial, error, embarrassment, a child needs family standards to fall back on, reliable habits of thought and feeling that provide security and protection.”
—Neil Kurshan (20th century)
“There are ... two minimum conditions necessary and sufficient for the existence of a legal system. On the one hand those rules of behavior which are valid according to the system’s ultimate criteria of validity must be generally obeyed, and on the other hand, its rules of recognition specifying the criteria of legal validity and its rules of change and adjudication must be effectively accepted as common public standards of official behavior by its officials.”
—H.L.A. (Herbert Lionel Adolphus)
“The standards of His Majesty’s taste made all those ladies who aspired to his favour, and who were near the Statutable size, strain and swell themselves, like the frogs in the fable, to rival and bulk and dignity of the ox. Some succeeded, and others burst.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)