All, thank you for your feedback and insight. Good lessons and info learnt and I had some good offline conversation with fellow members.
In sum: the issue has been resolved regardless of the root cause which I understand was likely a combination of Winchester factory and other items mentioned here. I trust the rifle maker who graciously fixed the issue and who also properly cleaned the rifle before giving it back to me. I have since resighted-in the rifle and the rifle now functions as intended and I cannot repeat the issue.
