Disappointed - Sightmark Tactical Red Dot Sight

First let me start by saying Optics Planet's customer service is the best and if you wish to purchase this red dot to see if you have better results they will work with you and make sure your happy. On to the review, there were so many things to like about this optic. The fit and finish was very good and mount was of nice quality. Mount gave absolute co-witness and brightness of dot was very good. Brightness control was stiff but for a battle rifle you wouldn't want the controls to be moved in the heat of battle. I went to sight it in and had it zeroed in no time. On my first copy I would lose the dot approx every several rounds. I would fiddle with the battery cap and it would come back. It didn't matter how tight I made the cap, I would lose the dot. I sent it back and requested a new one. RMA was painless and had the replacement in little over a week. Went to the range with my second copy and in the process of sighting in that one the brightness label feel off and the pin that holds the flip up covers backed out. I returned the SightMark and spent the extra money for a Vortex. Like I said, there were many things to like about this optic but sadly I can't recommend it. I hope SightMark can iron out their issues, I might be willing to try again.