I am not a weapons designer, this is purely to satisfy my own curiosity :) I would like to simulate a gun shot in a rifle barrel and determine the mode and freq. of vibration using a FE program (Code_Aster if anyone is interested), but I don't really know what transient load to apply. What components go into making the barrel vibrate? Shape of course, boundry cond. i.e. barrel to receiver connection etc. - but how would you describe the discharge of a round? Thanks in advance.