I wasn't satisfied with the fit of the front handguard.  I could feel a little wiggle in it and traced it back to the pinned lower band. I have the front handguard solidly attached to the band with screws and epoxy.   I loosened the four set screws in the top of the scope mount, leaving the saddle screws tight and using a punch on the saddle I tapped the handguard/mount forward into more solid contact with the lower band.  Got it all back together now, barrel nicely centered, and got rid of the wiggle.  There's now about 1/16" gap between the front of the receiver ring and the rear of the mount.  Should have tapped that mount forward last time I assembled things!