One of the best sights I have ever used is the EoTech. I ran that sucker for many years over the pond. It never failed me, as long as I kept fresh batteries in it. One of the “tricks” I learned years ago is how to quickly sight it in and verify that 50m zero.
I prefer the older style EoTech sights myself.
Here’s the Amazon site. EoTech
Here’s a nice little charm on eBay!! EoTech