Is it possible to fire a random ordnance at a random time? For instance, say you have ten ordnances. Would it be possible to give each of the ordnances a 10% chance of being fired without the other 9 ordnances firing? Kind of like how you have like a 25% chance of dropping health instead of ammo when you die. If this is possible, how would I set it up?

have to try it myself but dont think it works

I don't know if random ordinance is possible, but I never really tried to do so either. If you can't find a way to do so, you might try a chargeable weapon. In that scenario, you can just place a whole bunch of charge levels to create the effect of randomness.