How many rounds have you put through it? The gold dots and Hydra Shoks are both Nickle cased too, right? So your gun has a problem with brass cases. I'm going to say something with the extractor; not sure how you could try and fix it yourself...maybe take the extractor off and get it really clean? (could you be missing some grime in there???)
www.xd-hs2000.com has disassembly instructions
edit: If you do try this, I recommend doing it inside a gallon bag, at least the first couple steps...that way you won't lose springs