The 5.7x28 shooting results we're aware of so far are promising. I will try to tune you in on some accounts..
- The Lima, Peru siege (known as Chavin de Huantar, see here for some more info on the operation itself) occurred in 1997 when a number of terrorists took over the Japanese embassy in Peru. The Peruvian CTs were carrying suppressed P90s. In the siege, two terrorists were killed with one 5.7 round each, and a third with two rounds. All of these subjects were wearing Level IIIA vests. One of the terrorists killed with one round was the leader of the group who died instantly upon being shot. The SS190 was the round used in this incident.
- Grand Forks, North Dakota SWAT had a shooting (the first ever with 5.7x28 in the US) with their P90s in 2000 that resulted in a near-instant fatality. Unfortunately, those are the only details from the shooting that I have been able to find.
- The shooting in Texas was the Houston, Texas SWAT team; it occurred in spring of 2003. A subject wearing heavy clothing was firing at HPD with an AR15, and he was hit with a burst from the P90, dying (by all accounts) instantly. Supposedly "the coroner remarked he had never seen a wound like it". These are comments on the incident from people from or in contact with HPD. Here are some comments on the shooting from Sandy Wall of Houston PD: "The 5.7mm ball produces a wound cavity about the size and shape of the best 9mm 115 grain JHP +P+, except the peak occurs at a deeper penetration. In the one shooting we had with the P90, the bullet performed well. In fact, the bullet performed exactly as it was designed. The autopsy provided detailed information about the wound cavity and travel of the bullets. None of the 5.7mm rounds fragmented and as far as we can tell, none exited either."
- Birmingham, Alabama SWAT had a shooting in mid-2004 with the P90. Here is a news article on this one with a bit of info on the situation.
- Doraville, Georgia PD had a shooting with the SS190 (most likely from the Five-seveN pistol, although Doraville does use the P90), resulting in a fatality from a neck shot. The subject's spine was severed but the round did not exit his neck. Another shooting, with Duluth, Georgia PD resulted in the subject being struck in the head with an SS190 out of a Five-seveN. It is true that both of these cases involved outstanding shot placement. However, it might be worth noting firstly that the rounds did not exit in either of these cases, and yet they did seem to do the job as well or better than other pistol calibers would have. Secondly, this outstanding shot placement could easily be attributed to the very low recoil and shootability of the 5.7x28 weapons.
- Sioux Falls, South Dakota SWAT shot a subject "in the hand and arm through a solid core door". He lost two fingers off his gun hand and the bone in his arm was shattered. After passing through the door, the round began to go into tumble and struck his arm flat, powdering the bone within. AFAIK this was the first shooting with 5.7x28 where the victim survived.
- I am also aware of a security firm working in Iraq that issues both the P90 and Five-seveN, and has shot multiple subjects with them. To quote a first-hand witness: "I have seen 5 people who were shot by the 5.7, all by some KBR security guys in Iraq. Three by P90, and two mixed P90, 5.7, and M4. All were DRT, going down almost instantly from the hits, and bleeding out right there."
- Here is a post over on another forum with an account from Iraq. It could be considered a bit shaky but I will hold back no info on the subject.
- Jacksonville, FL SWAT has been using the P90 for several years now and to date has shot three subjects with it. According to statements made by one Jacksonville officer, these subjects were shot several times; some may attempt to use these case(s) against the 5.7x28, but we still don't know the hit locations in any of these shootings.
- I am aware of another recent (fatal) case in Austin, TX where a man was shot once in the heart (bullet entered above the right nipple and exited under the left shoulder blade) with a civilian round (of unknown type, possibly SS197) out of the Five-seveN pistol. A first-hand witness described the wound cavity damage as minimal; coupled with the claim that this round exited the body (this is the first case I'm aware of where a 5.7x28 round exited the torso of the victim) and "blew a heck of a divot from the concrete wall [behind the victim]", I'm assuming this was an SS195/SS197 that kept going and possibly failed to expand/yaw. Regardless, the bullet still got the job done, demonstrating once again that shot placement is everything.