acceleration as it is spun up by the rifling in the gun tube once the projectile leaves the gun tube the setback acceleration ceases but the spin continues at a more or less constant rate the sequential action of setback tube exit and spin are the environments the invention exploits to validate launch and mechanically arm the weapon during a normal launch event with the mems s amp a oriented as indicated in fig2 with the shown travel and acceleration direction 39 and preferred location of the weapon spin axis 38 the setback acceleration drives setback slider 21 downward through the zig zag inertial delay engagement between setback slider rack teeth 212 and setback slider zigzag rack 19 until it leaves the engagement and goes into free fall as the slider travels down setback slider travel slot 202 within the arming slider 20 with continued launch setback acceleration slider 21 gathers speed and then pushes past and deflects latch barbs 215 and stops at the end of the travel slot in the configuration of fig6 this completed action is referred to as removing the first safety lock or interlock in the inventive device in the configuration of fig6 the 1 st safety interlock is removed from the arming slider 20 but the arming slider cannot advance toward arming even with the.