I do not believe the Fraser pictured is anything more than a trade action filed up and fit by them, likely after the namesake had died. While it does have intercepting sears, the pivot is not located on the trigger plate like a typical Fraser. This is what a real Fraser boxlock looks like.

https://jamesdjulia.com/item/lot-1270-ex...nal-case-33448/

This one is a rifle but it does show the internal workings very well.

http://www.bertramandco.com/
Booking African hunts, firearms import services

Here for the meltdowns