My Bersa Firestorm .22 LR was a little balky when I first got it. Running only 9 rounds of CCI Mini Mags per magazine helped until the mags and gun got worn in. 10 rounds in the mags wouldn't feed correctly in the beginning.
Going by memory, I did two other things to my Bersa.
#1 is to make sure the recoil spring's cut off ends aren't dragging on the inside top of the slide. I make sure to position the cut off coil ends under the barrel, not on top of the barrel. I used a Dremel to smooth those cut off ends, as they were burred from the factory. On mine, one end of the recoil spring has a slightly smaller diameter than the other end. Slip the tighter end onto the barrel and let the looser end fit into the front of the slide.
#2, I used fine grit sandpaper (maybe 1200, don't remember) to polish the tooling marks on the exterior of the barrel. That seemed to let the recoil spring and slide move over the barrel with less resistance. It sure reduced the "zing-zing" sound while hand cycling the slide slowly. I also use a thin smear of gun grease around the barrel to let that spring and slide slip on by.
I don't recall if I did any thing else at this point. If something comes back to memory, I'll be sure to add it in.
