Saw a heli with the grey JR ball links with the metal ball and thought they were great, ordered some and not a single one turned out to be free of slop so I don't know how the ones on the heli I saw were slop free?? There's no way I'd need the ball reamer with the ones I got, I guess I just got unlucky.

I use the dubro ball links with the brass balls. You can put the ball in the link, then place that into a vise (flat jaws of course) across the flat of the ball and then tighten it up and it will expand the brass ball for a perfect slop free fit. Been running mine in a IC ship for a couple of seasons and they seem to be holding up well....