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The first powders were called "MR" for military rifle powder. In the 1920s these powders were improved and the name was changed to IMR. Various different powder are produced and are given numbers to distinguish them. The different types of powder typically have different burning rates.
The C was to indicate the powder burned "cooler" than traditional Improved Military Rifle (IMR) powders. [4] In 1949, he began acquisition of powder salvaged from disassembled Oerlikon 20mm cannon cartridges. This powder resembled IMR 4350 in appearance, and with a slower burning rate, was initially marketed as "4350 Data", and later as 4831. [5]
By manipulation of the shape it is possible to influence the burning rate and hence the rate at which pressure builds during combustion. Smokeless powder burns only on the surfaces of the pieces. Larger pieces burn more slowly, and the burn rate is further controlled by flame-deterrent coatings that retard burning slightly.
This graph shows different pressure curves for powders with different burn rates. The leftmost graph is the same as the large graph above. The middle graph shows a powder with a 25% faster burn rate, and the rightmost graph shows a powder with a 20% slower burn rate. Energy is the ability to do work on an object. Work is force applied over a ...
Improved military rifle propellants included a longitudinal perforation converting each grain to a tube with a progressive burning interior surface allowing a more consistent gas generation rate through the reaction period. Early propellants were identified by a two-digit number.
Ball propellant (trademarked as Ball Powder by Olin Corporation and marketed as spherical powder by Hodgdon Powder Company [1]) is a form of nitrocellulose used in small arms cartridges. Ball propellant can be manufactured more rapidly with greater safety and less expense than extruded propellants.
Hodgdon also makes "Triple Seven", a sulfur-free black powder substitute containing potassium perchlorate and 3-Nitrobenzoic acid, and "Black Mag3". [10] These are both more energetic by mass than black powder and can produce higher velocities and pressures.
Source(s): Accurate Powders load guide v3.5 [1] Hodgdon powders achieve approx 100fps less. [ 2 ] The .300 Winchester Magnum (also known as .300 Win Mag or .300 WM ) (7.62×67mmB, 7.62x66BR) is a belted , bottlenecked magnum rifle cartridge that was introduced by the Winchester Repeating Arms Company in 1963.