Ian from Forgotten Weapons just released a video on this interesting revolver. It's a 357 Magnum used by France's elite GIGN police force starting in the early 70's. They apparently had some strict requirements for this gun including accuracy and durability for a very high round count. They had a standard carry version along with this strange sniper version.
I had never heard of these before this, but I'm not familiar with French revolvers. I wonder if any of these ended up in the US?
https://www.youtube.com/watch?v=P1zEUGck8NE