Something that will deliver more instant incapacitation.
incapacitation: is that a word?
The .40 came about from a police FBI shootout in Florida with criminals wearing armor. I am sure there were earlier calls for stronger LE rounds but this incident was the last straw. They complained of 9mm and 38sp ‘bouncing’ off the criminals and earlier complaints of 9mm taking too long to incapacitate an enraged or highly drugged perp.
They had trials with newly developed 10mm but it was too much, causing other problems... namely second shot accuracy and the liability that they foresaw in a wild second shot. They settled on the slightly lighter and cooler .40cal and it has gained popularity quicker than any other round in LE and in civilian markets.
Thanks for your reasoned argument BUT that tells me, a .44 magnum should the round of choice. But no, the 40 S&W and the 9mms seem to be the preference of most police departments.