P-10C malfunctions are rare in my experience. I've run about 2,500 rounds through mine, all but 100 or so my reloads, with a grand total of zero malfunctions of any kind. I'd chock your first magazine issues up to a tight gun. The slide should run more freely in short order and you can wrack by merely thinking about it. I use a light grease that's infused with teflon on the rails.
I do find there's a lot of breaking-in to do on a P-10C. The magazine release was really stiff as delivered, and the slide release was hateful. I worked over the mag release parts and got it rather nice with little effort and some more grease. The slide release breaks in on its own in its own sweet time. I recently realized if you insert and smack a loaded mag on the base plate with gusto (palm strike) the slide drops on its own, saving you a blister.
My gun is accurate with a wide range of bullets (like everything) and I've had no copper fouling problems. I have used CFE Pistol nearly exclusively, which does seem to reduce fouling substantially.