[/quote]While instinctively I agree with you on Vaseline, I went back over the Purdey website Because old Purdey manuals actually recommended Vaseline on the locks. I suspect at one time Vaseline was defaulted to as it was easily available and much of the better things we have today did not exist. I went back to the 1929 Purdey instructions state “slightly greased-we prefer Vaseline for this purpose.” I found buried within a current video on Purdey’s website a Purdey employee still recommending a 3-in-1 oil Vaseline mix for action parts.

Why would “slightly greased” with Vaseline be bad?

What specific lubricant would you suggest on a SLE’s locks and why? [/quote]

Purdey still recommends Vaseline or a 3-in-1 oil Vaseline mix. Several years ago at the Southern SxS I saw a jar of Vaseline and asked the vendor if that is what they recommended - he said yes, that was what all of their gunsmiths used - it was Trigger (Alborough Tregear) the managing director of Westley Richards.

If Vaseline is good enough for Purdey and Westley Richards it's good enough for me.