Redneck: In answer to your question - yes, setting the fuze to zero is extremely dangerous and is only done is real world emergencies (as in the bad guys are about to over run your position and have to be stopped now :!: ) and you can't duck Killer Junior like you can a flechette round.
All time fuzes have a built in 3 second delay before they function as a safety (so they can clear the tube), but you run the risk of the base of the round hitting you if the round goes off within 300 meters of your position.
BTW, the P90 Personal Defense Weapon is made by FN and fires a special 5.7mm high velocity cartridge developed for it (not a .357 magnum) and is properly classed as an advanced submachine gun. FN also developed a pistol that fires the same round, the FN Five-seveN.
I'd rather be a Soldier with a mule and mountain gun, than Knight of old, with spurs of gold, or Roman, Greek or Hun. For when there's trouble brewing, they always send for me!
Mortui Non Mordent - Celeritas Et Accuratio