After misfire, second ignition attempt resulted in almost instantaneous blowing off of the nose cone while the model was still on the pad. Upon removal of the motor, the nozzle was damaged and the case was split down its entire length. The forward closure was blown up into the model where it was trapped by the ejection baffle. The ejection plug is still in place and the delay element looks unburnt. I think the nose cone was blown off by propellant gases getting by the forward closure and O-ring as the case split.