It lasted about 30 rounds I think but didn't notice when it left. I was sighting in a Fastfire III I had mounted when it departed. I talked to a nice lady at Patriot Defense who does competitive shooting there. She lost one also in the middle of a round. She mentioned putting a bigger screw in the Dawson sight. I suggested to her that the problem would probably be solved by a tighter fit in the dovetail. Even if a little filing is required it will fix the problem with a snug fit.
I will wait and see what comes on the market. Right now I am VERY pleased with the Fastfire and it showed two distinct advantages and what I was looking for. Accuracy at hunting distance and night hunting capabilities.