Accession Number : AD0907041

Title :   Performance of 20mm and 7.62 mm Ablative Ammunition.

Descriptive Note : Final rept. Jul 71-Jul 72,

Corporate Author : CORNELL AERONAUTICAL LAB INC BUFFALO NY

Personal Author(s) : Brown, W. R. ; Baran, W. J. ; Sudlik, D. J. ; Vassallo, F. A.

Report Date : JUL 1972

Pagination or Media Count : 92

Abstract : M55 A2, 20mm ammunition modified with gelled dimethyl silicone to reduce barrel heating and erosion was found to cause heavy coppering in unplated M61 barrels. Extensive single-shot and burst screening tests of decoppering and lubricant additions to the silicone were fired. The one candidate silicone-modified (ablative) ammunition showing good promise in unplated barrels was that having projectiles with sintered-iron rotating bands. Limited testing in chrome-plated M61 (Vulcan) barrels indicated that the performance of the silicone- modified ammunition in chrome-plated barrels was highly promising. Coppering deposits were nearly stable in thickness after the first 175-round burst, and no measurable erosion took place in the test barrel and in the 973 rounds fired. Silicone-modified 7.62mm ammunition was also studied. Erosion tests in unplated M60 machine-gun barrels indicated a yaw life of 7595 rounds versus 4419 rounds with standard ammunition. Limited firing of 2800 rounds of silicone-modified ammunition in lined and plated M60 barrels indicated that much greater life improvement than the above-mentioned would be expected in chrome-plated barrels. Barrel heating reductions due to the effect of the silicone ablator were measured. Tests were carried out of the cook-off performance of ablative ammunition in M60 barrels modified to simulate the Minigun. An increase of at least two:one in the single burst length safe against cook-off was estimated for the Minigun. (Author)

Descriptors :   (*SMALL ARMS AMMUNITION, ABLATION), (*GUN BARRELS, EROSION), FIRING TESTS(ORDNANCE), DEPOSITS, INTERIOR BALLISTICS, SILICONES, SILICON DIOXIDE, LUBRICANTS, HYDROCARBONS, GELS, PLATING, CHROMIUM, GUNS, MACHINE GUNS, COOK OFF, YAW, HEATING, CHROMIZING.

Subject Categories : Ammunition and Explosives

Distribution Statement : APPROVED FOR PUBLIC RELEASE