The following filler materials are recommended: Whenever inconsistent velocities are detected, it is recommended that a proper filler material be used to keep the powder at the primer end of the case. The higher inertia ensures better ignition and combustion. Use the heavier projectiles for a particular calibre. This will ensure better stability due to a more centered COM (center of mass) Use projectiles with the shortest ogive possible, preferably Round nose projectiles. This is indicative of extremely low pressures which, is an early warning sign that bad ignition "squib" loads = stuck bullet maybe eminent. Make sure that projectile has left the barrel when a blackened/sooted case is extracted.Īlso be aware when extremely low velocities are recorded < 900 Fps. The loading is done inversely to the standard practice with normal loads and is best executed by loading from a higher Velocity usually in the 1300-1400 fps range towards the lower level.Ĭonfirm statistically, with proper number of rounds per iteration (min 10 rounds) by measuring the velocity with a chronograph and verify standard deviations and extreme spreads to make absolutely sure that no supersonic “flyers” occur. Neck-sizing the cases to ensure proper obturationĪdding Fillers to keep the powder on the primer side of the case (Dacron® or Pufflon® – see below). To ensure the best highest possible loading density, select the bulkiest powder with the lowest bulk density (weight/Volume).Įxtruded flake, or -tubular or -multi perforated powders, are usually the recommended types, however there are some exceptions utilizing special spherical/Ball® powders. However, there are exceptions involving slower burning powders with excellent ignition characteristics such as our Accurate 5744® In most cases extremely fast burning Handgun/Shotgun powders are the better options. Begin at the recommended minimum/Start loads and incrementally load lower towards the subsonic range, of between 10 Fps. Use any well-known Cast Bullet Publication, such as Lyman®, Speer® etc as a guide with the above equivalent powders. Use only powders with good ignition characteristics. Warning: - Since fast burning powders are used, it results in very low loading densities Therefore the possibility of double charging is very high!! - Please take extra precautions to prevent this from occurring. Subsonic loads using standard components will not cycle high power, semi auto rifles. Therefore, it is actually a waste /moot point shooting with these designs at subsonic velocities. Projectiles with sharp pointed ogive’s do not make good subsonic projectiles becauseĮxternal and Terminal ballistics at subsonic velocities does not exploit the design features of high BC jacketed SP or HP-BT bullets. This leads to low loading densities, which might cause ignition problems.īecause the requirement is to have subsonic velocities while maintaining the best possible combustion efficiency, the velocity should be kept as close as possible to the sonic threshold for the specific conditions, preferably between 1025 Fps to 1100 Fps. Therefore faster more efficient burning powders are required. This means the combustion efficiency is not good. The practice of down loading rifle calibers to subsonic velocity levels must be approached in a special way.Īt subsonic velocities the chamber pressure is extremely low in most rifle calibers.
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