Analysis of Circumferential Case Rupture.
Technical research rept.,
FRANKFORD ARSENAL PHILADELPHIA PA
Pagination or Media Count:
The results of an Analytic Investigation of circumferential ruptures of the case sidewall of 7.62mm Brass Cases are presented. The failure is located approximately 0.3 inches from the primer end of the case. The failures considered only occur in the M219 machine gun and are assumed to be weapon related. The investigation examines two possible causes for the failures by comparison of rim shear strength, extraction force, axial strength of sidewall and stress levels in the case of several different loading patterns. Results of these calculations indicate that it is not possible for the case to be failed by excessive extraction force applied to the rim at time of extraction. However, a model of case chamber interaction during chamber pressure rise to peak pressure does predict failures of the type known to occur in the field. Failure according to this model is a function of bolt deflection and coefficient of friction between case and chamber. Possible solutions to the problem and recommendations for further investigations are given. Author
- Ammunition and Explosives