Brummel Splice in Samson Extra

[bigwhitesofadog]

I am trying to use a Brummel splice to put a shackle in the middle of my new Samson Extra sheets. I can't get a large enough hole in the rope to get the end through. The cover is pretty tight. I thought if I could get the core out, I could do the core and cover separately, but that isn't working either. Any ideas?