You probably don't want one. The round is very expensive, and hard to come by. The original purpose of the round was armor penetrating possibilities. It can do this because of it's velocity, and the fact that it is pointy. The round is very similar to a .22 Hornet. I would think there are many better choices for defensive purposes. I know little about the pistols, aside from the fact that the grip is very long front-to-back. The pistol is very large in most dimensions.
What exactly is drawing you to this particular pistol?
While 5.7x28 is a very small cartridge and it's not cheap, but it ****s up meat in an unnatural way compared to conventional ammo. I'm not sure why it does the damage it does, but I would not want to get hit by one.
Yep, as Phatcyclist said, these guns would not do very well as a self defense gun. If you are interested in one purely because they look cool and you like them, there is certainly nothing wrong with that. For just general plinking it would be pretty expensive, and you might want to consider something in a more common and inexpensive caliber like 9mm or 22lr for plinking purposes.
The whole concept behind this 5.7x28 caliber (as far as I understand it anyways) is that with all that velocity and a small pointy round you will have all this energy focused on a very small point which makes it considerably easier to penetrate through body armor. In some ways it is a similar principle to the way those window breaking devices work. As far as I understand it, that is really the only ballistic appeal to these guns. They do hold 20 rounds and they are bullets so they are still deadly however with such a small caliber you wouldn't see near the expansion of something like a 45acp or even a 9mm and because of the high velocity I believe there is also a very real possibility of over-penetration though I'm sure they make hollowpoints for them to help prevent this. From what I've seen, it appears there are various 5.7x28 loadings anywhere from 1700-2200fps. There might be some higher or lower but it seems that most types of ammo for these guns have velocities in that range.
Joey, what is the main appeal of the gun to you? If there are certain characteristics about it that make you want one, there might be some other guns out there that share similar characteristics and would be much more economical and that you might like as well. As always, if the answer is you just like them and want one, there is nothing wrong with that and more power to you.
FN builds a pretty good pistol, but as others have said above the gun isn't necessarily economical to shoot. One thing to consider is the availability of common ammo, and the adaptability of the pistol for what you need it to do.
I feel 9mm is the superior carry round. This is simply my opinion. I base it primarily on the ease of control, capacity, and capability of the ammo. My second choice would be .45 ACP, followed by .357 Sig and .40 S&W. Really you can't go wrong with a standard caliber, it's all in what you feel comfortable with.
Oh, I have no real reason for wanting one. I've got my Kel-Tec .380 for carry and I'll get another S&W .357 for home defense and taget shooting. It's just that thing is sort of the Ferrari of Handguns, Exspensive, exotic, and cool looking. I remember reading about them when there were still only available to military and police. It sounded sweet. 20 rounds of high velocity shortened rifle ammo. What's not to like. Sure the bullet itself is tiny, but at the speeds it operates at, it ****s **** up. I mean hell it's the same bullet as in an M-16, just in a shorter case. I'll probably never get one, but if I come across one someday at the gun store and I've got a bunch of money burning a hole in my pocket, I may.
If you want an expensive "Ferrari" of handguns, here's a few you might want to check out sometime:
-H&K P9S (I have one and you are more than welcome to shoot it any time)
-Sig P226S, P229S, P220S (S = Sport)
-CZ75 SP-01 Custom Shop (aka Sp-01 Shadow, I believe)
-Any Wilson Combat or Ed Brown 1911
-Walther P99 (cheaper "Ferrari", but one of the best double stack 9's out there IMO)
That is all I can think of off hand though there are plenty of other guns out there that fit the bill. I highly recommend checking out the HK's I mentioned, as they were built with the high performance and precision of a Porsche or Ferrari, have really light absolutely AWESOME triggers out of the box, are dead on accurate and just neat guns overall. My P9S has about a 3.0-3.5# trigger out of the box stock, and with it's polygonal fixed barrel (not a browning tilting barrel design) it is insanely accurate. Here's an excellent (but long) video on the P7:
I have both the European and US version. I like them The ammo isn't any more expensive than any other ammo. A box of 50 rounds run $17. A box of 20 to 50 rounds of 9mm JHP (Fed Hydro shock, Rem Ranger, CorBon)etc. runs how much?
You can get both HP and ballistic tip rounds for about the same price. The gun with 20 rounds is LIGHT. The whole gun and mag weigh about as much as a loaded sig .45 mag.
The gun has no kick at all. The nice thing is the PS90 (rifle) uses the same cartridge in a 50 round mag!
I think it is a great gun to keep around. Ammo is light, effective and the down side is the ammo isn't available all over the place. If you aren't careful you will get screwed on the price of ammo.
Locally from Academy I've found 9mm Blazer Aluminum for $7.99, WWB 9mm ~$8-8.50 and you can usually get a box of 50 run of the mill JHP's from Winchester for ~$13-15 I believe. The Corbon PowRBall I like so much is usually around $19-22 I think. Ammo supply isn't too much of a big deal considering you can easily order the stuff off the internet, though in a bind going to the range at the last second it could be a bit hard to find. I'm pretty sure Cabela's always has some in stock though.