Is it normal to be able to rotate the rear sight on A2 upper about a few degrees from left to right? This just seems like it would make the upper were difficult to sight if at all? Any suggestions as to how to remove the play from the rear sight? Thanks

The play/twist in the rear sight is normal.

There is a single detent and spring in the left side of the sight housing only.  This makes the sight housing track the right side of the upper receiver as the sight is rasised and lowered.

That was my assumption, thank for you answering the question, I appreciate it.

I put a dab of JB weld on the oppposite side of the rear sight from the spring (at the bottom, the same as the spring).  I then dressed down the bump of JB until the the front sight was in alignment with the bore.  This doesn't help accuracy much on a rear sight that doesn't have a hood, but I think it looks better!  Make sure you clean the metal with degreaser before you apply the JB.  It doesn't hurt to rough up the metal a little with a fine grit sandpaper first also.  I'vd heard of others using pieces of a feeler gauge or a small weld bump.  I thought the JB was easier, and it hasn't worn or fallen off in years time.

This play is normal, as long as the sight returns to position when you let go of it, under spring pressure.  I've shot plenty well with sights like this.