I had the exact same thing happen with my HP22A when new, using Federal Auto Match. So I know that if you turn the brass over, you'll find the FP dot on the opposite side of the rim from the bulge. I did some tweaks to my gun, and this went away. I'm not 100% sure about how or why, but I have a pretty solid theory.
Check the notch that is cut out of the breech where the extractor fits. It's a tight fit. On mine, you could see where the extractor actually got pushed out a little by this notch when the slide was returned to full battery. But if the slide was slowed by the chambering of a round, it is conceivable that instead of the extractor getting pushed out, the slide might get hung up just a tiny hair out of battery, instead. I took a file and deepened this notch just a tad so that it wouldn't contact the extractor. Actually, if memory serves, I didn't have a file thin enough to fit, so I ended up using a Dremel, a cutting disk, and a really light touch.
Yes, it seems ironic. To stop the brass from bulging you have to remove a little bit of the chamber support.
But I am pretty sure that was the cause in mine.
Check the jimenez arms forums for more info on tuning up this pistol.
