I have a Oly .223 (I don't want to hear any flames about it.  It shoots great and it serves its purpose) and have noticed that is has MUCH more movement in the selector then my Colt that I just bought.  Is this normal for Oly's to be so loose?  Maybe it has always been there and now that I have a Colt which is really tight I am noticing it now.  
I can tell that my Oly's upper is tighter on the lower then my Colt is.  Maybe I will get an AcuWedge for the Colt to tighten up the upper.  Anyone else have these problems???

The easy fix to tighten up the selector is to just replace the detent pin and spring. You can replace both parts by just removing the pistol grip.

The detent pin will have a point, and depending on how sharp the point is, will apply pressure to the grove in the selector grove.  If your point is dull, and the spring is a little weak, then the selector will turn very easy, and rattle a bit.

P.S. In time, the Colt will loosen up too, it's just the the Colt selector is new(bearing surfaces) and the detent pin is sharp.

I just tried to change out the detent and the spring with brand new stuff from GP.  Its about the same as it was before.  I think I will have to get used to it.  But for some reason I don't remember it being that loose.

It may just be a crummy selector.  I got a loose one in a DPMS lower parts kit.  Tried another one which was much tighter.  So, the loose one is now in the box o' parts.