Wow, it's been a long time since I heard about a Megastar. How long have you owned it ? Have you had trouble with that load before, or did it start acting up with the 250 gr ? I've never heard of anyone using that heavy a bullet in a semi-auto pistol. Could be too heavy or too long. What is the overall length of the round ? You may also need to replace the extractor spring. I'm not that knowledgeable on the Megastar, but that's what I'm thinking. Can you post some photos ? Would love to see a fairly rare pistol.