The Russian Mosin Nagant Forum

Found this YouTube channel has some really good videos. Check it out if you haven’t already.

Actually it's C&Rrsenal. They've been around for quite some time. They've rally taking the knowledge of these guns to the next level of understanding.

They also do interact with other gun experts who have YouTube channels like Ian from Forgotten Weapons or special interest channels like The Great War. Both of those channels are well worth watching.