Hey Casimir. I had the same problem with mine. Seems to be a fairly common problem. I cleaned my firing pin channel but that only made it fire a few more shots before it would light strike. The firing pin strikes were way off center as well. I think this is due to the firing pin channel being drilled wrong. I contacted Kel Tec, send them my slide and barrel. With in a week, I had a new slide and barrel at my front door. I will admit, I haven't really tried it out yet, but I did fire 14 rounds (Rem UMC HP) of the ammo I had ther most trouble with. All went bang and strikes seemed pretty centered now.
It's easy to be upset with Kel Tec for letting a gun go out like this, but they will make it right. -Actually, now that I think about it.... Before i send it, I convinced myself that it would be ok if I only bought Federal ammunition. For what I read, this ammo has soft primers and I did NOT have light strike with it...The empty case from the round they used to test fire, if I remember correctly, is a Federal.