I totally thought this was a screenshot from The Witcher 3 at first.
I totally thought this was a screenshot from The Witcher 3 at first.
A quick google of “Reflector Sight” shall give you the answers you seek. https://en.wikipedia.org/wiki/Reflector_sight
Scroll down a little and you’ll see a picture of Howard Grubb with his prototype sight on a rifle in 1901.