The newer style NGC slabs are a bit more difficult. Instead of two halves joining together on the side, the top piece of the slab rests down inside the back piece, so the old method of just tapping around the edges to break the seal no longer works.
I've found that hitting a corner to crack/shatter a piece to come off and them using a pliers to move around the edge of the slab and break off the rim seems to work.
Craig
Yes, the new
NGC slabs are quite difficult to get into.
Some time ago I got a Cnut penny (see below) in one of the new
NGC slabs. The coin is no thicker than a thick piece of paper, and so is very fragile. Vises, pliers, and hammers were out of the question. In the end, I placed the slab between 2 pieces of
wood in a vise to hold it steady, and then used a saw with a very thin blade to saw off the bottom of the slab. I was then able to get a small screwdriver into the bottom of the slab. Using a twisting and prying motion with the screwdriver, I was able to
work my way up both sides of the slab until the top piece popped off. One piece of advice: Go slow.
https://www.forumancientcoins.com/gallery/thumbnails.php?album=4762