Have you checked the primers on those reloads? Any chance they are not fully seated? Shouldn't only hang up on one particular cylinder if that is the problem, but its a thought. Otherwise, I agree with previous posts about thoroughly cleaning cylinder, extractor star, chamber mouths. Maybe some bullet lube is gunking something up, or a shard of lead. You might have a local smith look it over before taking the time to send it to Ruger. Good luck. My security 6 just keeps on going.