connecting element 381 to connect the tip 358 of the rotary striker 351 to the inertial igniter structure 352 as shown in fig1 the connecting element 381 in this case a shearing pin is then designed to fail i e break to shear and release the rotary striker 351 at the desired spin acceleration level in general the shear pin 381 can be provided with a notch 382 to concentrate shearing stress in that section of the shear pin 381 to achieve more controlled shearing at the desired spin acceleration level another alternative method of achieving rotary striker release at the desired spin acceleration level is the use of a detent pin 385 as shown in the schematic of fig1 the detent pin 385 is attached to the inertial igniter structure 352 and its locking ball 386 which is biased forward by the preloaded compressive spring 387 engages the dimple 388 provided on the tip 358 of the rotary striker 351 the size of the detent ball and the depth of the dimple and its preloading spring would then determine the level of acceleration at which the rotary striker 351 is released during the firing in addition the elements such as the elastic element 355 providing the aforementioned resisting torque may be positioned at the rotary joint 353 and may be of a torsion spring type it is noted that the center of mass of the.