Am I going to be the only one here to defend the 40 S&W? I'm finding much more 40 S&W brass than 45 ACP at the range and actually slightly more than 9mm even! It gives more capacity, but still has great knock-down power. To me, it's the perfect compromise and is able to be in slimmer, easier to conceal guns than the 45 ACP. Now please, in NO WAY am I dissing either the 9mm or the 45 ACP, but for me, the 40 S&W is my go to round and it's popularity amoung law enforcement says a lot in my mind.