Just getting into splicing and working on putting a tight eye on Samson Velocity, and I cannot for the life of me get the hang of extracting the core from the jacket. I've tried a marlin spike, sweedish fid, and wire fid.
Try an awl, slip it under two strands of the cover picking them up and out slightly, then take two more on the opposite side.
Keep lightly pulling the loops of the cover strands and open a ‘window’.
You only should need to pick the strands about 1/4” or so.
The cover has to open here anyway to burry the splice, so it’s good to relax the lay a little, just don’t go over kill
I use a rounded small screwdriver, bunch up cover as Nick said, insert parallel with rope first, make sure it is in between strands, if through a strand it won’t open up as much. Once it’s in, turn ninety degrees and run it around the inside between the cover and core. While trying to push it out, widen the opening by pushing the strands individually. It’s best to extract the whole core before trying to extract, but not always possible.
If really hard to extract, sometimes easier to extract the core at mark B instead A and then reinsert the end through the eye and extract, of course leaving a bight of core.
This video was posted to one of my threads and while it doesn't explain anything as far as where to measure, there is a great closeup up the core pull. The technique of pushing the strands to the side sequentially before going after the core is really helpful. I started doing it like this with good success.