Keep in mind that many guns require a reasonable break-in period, during which time a you can explore various rounds in the search for the "perfect" ammo that matches this specific gun. It's going to have tolerances that the next 238 won't have, exactly, and thus might well have a slightly different break-in period or preference for ammo.
After 500rds, I'd reevaluate. Ensure that you've got a number of magazine that you are cycling through, as well. If through a variety of ammo and magazines you still find you're having troubles with jams, then consider either the magazines or gun as the culprit.