That pinch is normal for an ABC or ABN piston and liner. If it's new, try to resist the urge to cold flip it through the pinch because you don't want to wear it down and damage compression. The liner and piston will change shape with heat and have a prefect fit while running. The new ones can be difficult to crank with the tight pinch. If it's a new piston and liner, to aid in the first runs you can lower compression with more head shims for the first run, and/or heat it with a heat gun, then crank it while it's hot. Don't do a rich break-in like you would with a steel liner, turn it on up to full scream, it needs the heat right away. You should richen it briefly and turn it back up, and keep doing this until it will hold a full speed needle without sagging. Bolt it on a plane and go fly. It will get faster and faster as you use it more.
Rusty
EDIT: Okay another post while I was writing. Now we've given you conflicting information. Maybe Bob's right. I thought it was an ABN. If a magnet sticks to the liner it's steel. If not, it's ABN or ABC.