One thing I found helps the CRC shocks is after you assemble the piston, shock shaft, and E-clips, hold the assembly by the shaft and roll it back and forth on a piece of sand paper. This takes the casting ridge off the piston and gives it just a little more clearance from the shock body, if you just assemble the shock without checking clearance you can feel the slight texture of the body inner surface binding against the body of the shock shaft... at least until it gets in a few good bangs and then it fits just fine.

I do this with all of my shocks anyway, i think it's just part of building a kit. It might not be necessary, but it doesn't hurt.