I was hoping that I could save a few bucks by getting an MI ERS instead of the the others that are more expensive and I notice that there is some side-to-side movement in the flip-up sight that pivots on the hinge pin. Its not a lot but enough to the point where its not going to hold zero. Is this something that is common to just this sight or do all flip-up sights have some play in them? Or is perhaps the sight I got defective?

Thanks ...Sprags

Sprags,
I have sold well over two dozen of the MI sets.  I have a set on one of my carbines.  As Troy mentioned they are spring loaded.
They don't shift in use.
I take them off and use them on different uppers when testing, and then back on mine.  I can still put a full mag into 6" at 300m with out any problem at all.
The MI sights are good to go.

Pete

Just to let everyone know...including Troy...I had no intention of of cutting down the product. I just wanted to know if this is normal. Upon close examination after Troy's response I did a closer inspection and It still seems that the movement is still more than it should be. Not only does the flip up site slide back and forth on the hinge pin due to the clearance between the sight and the uprights the hinge pin goes through but it also seems to rock some as well. I understand that there has to be some clearance between the features on the part but I don't think there needs to be as much as there is on mine.

Troy...I did call and leave a message on your voice mail. I would like to talk to you more about it.

I talked to Troy last Monday and I had a replacement on Wednesday. The replacement is much better. Thank you....Sprags

Good to see MI stands behind their product. I have a MI front buis and it's my favorite.

yeah I like MI alot myself they have very good cs and I went with the MI SPLP BUIS I just wanted somthing more low profile for under my TA31F but I love the BUIS. I take off my ACOG once in a while and use it just to keep up my skill with iron sights.