I don't know of any company that provides detailed interview feedback. This is best for the candidate and for the company both. Providing feedback is an absolute no-win for the company. Candidates will tend to go comparison-shopping based on the feedback that was provided. Worse yet, a determined candidate could twist the feedback in such a way as to sue the employer for discrimination. A candidate facing a rejection isn't in an objective state of mind when receiving the feedback. Your first instinct is to push back and/or defend yourself. You got rejected; the best step forward is to take it on the chin, analyze for yourself and move on. The most you can expect to hear from a recruiter is an encouragement to reapply in 6 or 12 months.
try contacting them again and asking what you should focus on preparing for prior to your next attempt in 6mo
LinkedIn msg to interviewers? Isnt that nosy?
Most probably not. You're only relevant until you interview. In case the recruiter does answer your email, he'll reply with "Our policy is not to provide feedback" unless you've a personal connection with the recruiter.