Standard muzzle velocity

A knowledge of the heat of explosion of smokeless powder is of considerable practical importance since the muzzle velocity of the projectile depends largely on this factor. For this reason the heat of explosion of manufactured powder must be checked from time to time. If the heat of explosion of a given lot of powder deviates from the specified value, then the necessary size of charge should be calculated to match the standard muzzle velocity. For this the empirical formula... 

Standard Muzzle Velocity. Velocity at which a given projectile is supposed to leave the muzzle of a gun. The velocity is calculated on the basis of the particular gun, the propelling charge used, and the type of projectile fired from the gun. Firing tables are based on standard muzzle velocity. Also sometimes called prescribed muzzle velocity ... 

The standard muzzle velocity of Schultze gunpowder is 1,220 feet per second. 

Computed Maximum Pressure (CMP). Value of max pressure computed by means of interior ballistic formulas. It will be developed when a new gun of a particular type is fired under standard conditions with a propelling charge which will give to the projectile its rated muzzle velocity Rated Maximum Pressure (RMP). Value of max pressure specified in the proplnt specifications as the upper limit of avg pressure which may be developed by an acceptable proplnt in the form of propelling charges which will impart the specified muzzle velocity to the specified projectile. Normally about 2000psi.above the computed max pressure, subject to determination at the time of development... 

The standard specifications permit the moisture content to range within certain limits. This enables the producer to regulate the moisture content to obtain the required ballistic properties. If the powder is too vivacious it should be moistened to the upper limit, while if it is less vivacious, the lower limit is preferable. In determining the moisture content the following practical rule should be observed. In rifle powder an increase of the moisture content by 0.01% lowers the muzzle velocity v0 by 4-5 m/sec and the pressure by 50-70 kg/cm2. In cannon powder the variations of ballistic properties are smaller and depend on the type of powder and on the calibre of the gun. 

Here, v is the muzzle velocity of the projectile in m s-1, m and M are the mass of the propellant and projectile in grams, respectively, and Q is the amount of chemical energy released by the combustion of the propellants in J g-1. The value for Q (also known as the Heat of Deflagration ) can be calculated from the standard heats of formation as shown in Equation 8.2. 

Service Velocity The muzzle velocity established as the velocity to be attained by a projectile of standard wt, under standard conditions of temp, when fired from a new gun of the designated type. Range tables are computed on the basis of this velocity Ref Anon, OrdnTechTerm (1962), 270-R... 

Tbngsten is available in the CM Tung-Shot line. This Hmgsten matrix material is slightly harder than a lead-antimony mix 11.2 gm/cm versus 10.8 gm/cm (or bismuth at 9-6 gm/cm ). The standard loads are 12-gauge 2 % -inch, with 34 and 42 grams of shot. CM notes that it uses an extra-hard machine cut wad for the protection of the barrels, and that muzzle velocity is 1378 fps. 

All subsonic rounds are loaded to produce velocities below 1100 feet per second, the speed of sound. This eliminates the "crack" produced by a normal velocity round when fired from a silenced weapon. These loads are also engineered to achieve reduced muzzle flash, greater muzzle energy,stopping power and accuracy than traditional subsonic ammo. An example of previous loads are the special 9mm rotands used in the silenced Sten during WWII. These rounds were similar to the standard. 380 load in performance. 

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