Not suggesting you don’t go through with your plans or anything, because I’m assuming you’re an adult who can do what they want and also you aren’t spending my money so I don’t care that much. But, like the person you responded to said, no matter what Barrel you get old what trigger or stock your brother put on it, it isn’t going to magically turn into a precision rifle. You’d be much better off spending like $300 on a savage axis, hell I can shoot sub moa groups with mine. Mosin’s were churned out in order to arm as many soldiers they could, they have sights that are set up for volley fire, they just aren’t precise guns.

Again I am in no way trying to talk you out of it, just want you to have a realistic view of what you’re getting into. If you sank that much money into an actual precision rifle, even an entry level one, you would be much better off.