How to Put a Scope on The Mosin (Quick Guide) – Escape From Tarkov
Items Needed: Kochetov Mount + PU 3.5 riflescope
To put all other scopes including Thermals refer to Part 2 here
Make sure your Mosin is Bolt Action Sniper Rifle Not Infantry Carbine
* Take note, there’s an item called Kochetov Mount already with the scope.