I just got my Aimpoint M2 a couple of days ago.  The only other red-dot I've used was a BSA.  I noticed that when the Aimpoint is on, depending on where the dot is in the optic, sometimes I can see a red ring around the inside perimeter of the optic.  The dot stays put on the target.  It's like the red light used for creating the dot is reflecting off the inside boundaries of the tube.  So I have this huge red ring the size of the inside diameter of the optic, and a little dot in the middle somewhere.  Sometimes, depending on head placement, I can see part of a big red ring, like I can only see the red light reflecting on the top half of the inside perimeter.

Does this sound normal for the M2?  I have never noticed this on the BSA that I used.  I haven't shot with the M2 yet, but it seems like it could be distracting.  Just wondering.  Thanks.

I just checked both of mine and I do notice a very dim red reflection of some when the dot is just about ready to go out of view. Have you tried dropping your brightness down a little bit? You also may try bumping the brightness down one notch.

Quoted: sometimes I can see a red ring around the inside perimeter of the optic

I see that in mine when I have it set on either of the two most powerful settings.

It should only be illuminated to the minimum.  If more, it causes alot of stuff like that.  Plus the dot turns into a giant fuzzy ball.

Okay, thanks guys.  I did notice that it is less visible when the brightness is turned down.  It depends on how bright it is in the room/outside, too.  I notice the ring on lower settings when I'm in a darker room.  Yeah, that brightest setting must be for aiming at the sun or something.  I like it about 2 clicks below the brightest, at least when I'm walking around the house with it.

For whatever it's worth, I pull Killflashes on all my Aimpoints, specifically for outside use. It helps increase the contrast at the cost of the slightly darker sight picture.