The Effect of Previous High Velocity Rounds on Zone I Muzzle Velocities and Copper Pressures in 105MM and 155mm Howitzers
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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It has been found that there is a monotonically increasing trend in Zone I velocities following high velocity rounds in 105mm Howitzer, M2E1, No. 3, firing Proof Slug, E2, and Shell, H. E., M1, and in 105mm Howitzer, M2A1, No. 79, firing Proof Slug, E2. Correspondingly, there appears to be a possible decreasing trend in copper pressures in both weapons firing both projectiles. This phenomenon has also been noted in the results of firings of 155mm Howitzer, T1, No. 2, firing Proof Slug, T11. The Zone I velocities in 105mm Howitzer, No. 79, firing Shell, H. E., M1, increased to a maximum, then decreased. The explanation of these trends as due to coppering of the bore and the use of decoppering agents to eliminate it have been discussed.