Hit and miss - Bushnell Tac Optics Big D Red Dot Sight

The first one of these I bought I put on an AR45 pistol build and it has been perfect. Very bright dot, huge field of view and has stayed spot on for almost 1,000 rounds so far. Enter #2: I purchased a second one for a 300 blk pistol build and it arrived defective. The dot would only show up on settings 5 and 6 and was not very bright so I sent it back for replacement. I received #3 and was happy that it worked as well as #1 out of the box. But, it went blank on the 5th shot and that was it. Sent that one back for store credit. I really want to give this this sight 5 stars since #1 has been flawless, but I can't due to the very poor performance of #2 and #3.