I use SS shackles from Deuce Factory. With those, they are made of a slightly softer material. Pete & Jakes are also slightly softer. I have never used TCI, but I have used a set from Speedway once, that came with quite hard material for the bushings. I ran a 1/2" drill through center, once they were pressed into the spring. Very little material was removed, and they slid right together.

Also like Don mentioned, some lube helps greatly.