heck, let's keep it going!
 

There is a lot of good information in this thread! As an Ammo Troop in the USAF, I get a h@rd-on for these types of topics.

After reading up on this for most of the morning, I found that all weapon systems are doing their respective “jobs”.

.45 is effectively killing/destroying things.

5.7mm is effectively putting little holes in paper, relatively accurately.

And 6mm airsoft is effectively keeping the neighbor’s dog from pooping in my yard. Well sort of, but I blame the intelligence of the animal for the repeated “shootings”.

No opinion on the .40 topic…

FWIW it is generally a good idea to consider the input of the subjects in the field as opposed to the input provided by the “experts” in the rear. If I were Barney, not only would I listen to the QP’s, I would also put the ultra-high capacity of both the p90/ps90 and the Five-Seven into the equation.

I find a .45 caliber hole staring at me a lot more intimidating than a 5.7mm hole. Sun-tzu said “attack few with many”, so I give me most caliber I can handle.:D

Something interesting about the 5.7 ammunition; what is currently available from the manufacturer to civilians really isn't good for much other than punching paper or small game.

A company called Elite Ammunition has been making some headway on that issue. Here is a link to their forums, specifically a thread covering some tests they have done:
http://www.fivesevenforum.com/viewtopic.php?f=8&t=1502

There they mention that one of their new production ammunitions is getting a muzzle velocity of 2600fps from the fiveseven pistol.

Perhaps this will allow the round to gain some more traction if they can get their supply issues cleared up.