Originally Posted by lndshrk
Yes - what would you like to know?
5.7 x 28 is a very effective round.
No it isn't. It is a .22 caliber bullet weighing in at 40 grains (civilian version) and has a muzzle velocity out of the FiveSeven pistol of 1650 FPS. That gives you a muzzle energy figure of 242 ft-lbs. That puts it between the .380 ACP and 9x19mm.
Due to the high muzzle velocity, it does have a good initial hydrostatic shock, but penetration is usually pretty weak (below 9".)
It has a 20 round magazine because, well, you are going to need all 20 rounds to stop someone!