This is partly a review, partly a warning on Keltec.
The Keltec PF-9 is a very slim and compact semi-automatic pistol. I have not looked into this pistol much and admittedly, do not know a whole lot about it.
That said, I have a friend with one and we went out to the range a month or so ago. We had an assortment to shoot from, a Glock 43, Ruger LCR in .327, and his PF-9.
His PF-9 had just come back from Keltec for service. It was extremely unreliable when he first bought it, so Keltec had him sent it off and they worked it over. It had not been fired since the service (where they fired rounds through it to verify). Using two different boxes of 9mm, it proved to be incredibly unreliable. We were having jams once or twice a magazine on average. Both of us shooting. Both boxes of ammo. Same ammo ran flawlessly through my Glock 43. We tried stiff-wristing it and limp-wristing it and it did not seem grip was causing the failures.
I recorded a video of my friend shooting it. He later contacted Keltec updating them that it was still not running well. He didn't hear back for some time. Finally called them and it sounds like he's going to have to have it serviced locally and that they were quite rude to him. Keep in mind, my friend is about as southern gentleman as it gets. He's patient, kind, soft spoken, honest, and about the last person to be unreasonable to get on anyone's nerves. If he got bad service, I think most anyone else would.
So to recap.
New Keltec PF-9 does not run reliably at all. I'm not talking about a failure to feed in a hundred rounds, but in a magazine or less. Goes for service, comes back. Immediately has the same issues. Keltec won't service it and is unresponsive.
To me, it sounds like the PF-9 is just a bad gun. When it did fire, it was one of the harshest and least enjoyable guns I've ever shot. My Glock 43, while a bit larger, is far, far, more comfortable. And I've shot a thousand rounds through it problem free, including reloaded ammo (there was one failure that was a mis-sized case, not the fault of the gun).
I think Keltec does have some good guns. I was interested in some of their foldable 5.56 rifles and their bullpups looked interesting. I've never had a bad taste in my mouth from them. And while I expect all gun manufacturers to have duds from time to time, here Keltec won't own up to it at all in this case. I now don't think I could buy one of their firearms. If you have one that's running well, obviously don't just chunk it. But I would recommend looking at other brands if purchasing a new firearm. If you want a small semiautomatic, the Glock 43 is an option, as is the SIG 365, or maybe even a Ruger LCP.
I will say that if the PF-9 was running reliably, with that much recoil you're going to get more shots on target (and have more effectiveness) with a smaller caliber or a slightly bigger gun. That said, .380s have seemed pretty unreliable to me. My Glock 43's recoil is managable and only a bit larger, and still completely reliable.
Update: I had a misunderstanding and Keltec did actually offer for him to send them the pistol back for a second time. Their attitude was pretty poor, however.