No way I would have upgraded the stock on a rifle shooting that bad. I’ve never seen a rifle improve by more than a half moa (off bags not bipod) by changing out stocks. I would borrow a scope, let someone else shoot the rifle, sale it , or be happy limiting yourself to hundred yard shots. What caliber is your friends rifles you shot moa with?
If you borrow a scope you don’t even have to sight it in literally mark where it sat on another rifle, remove the scope and put it on your rifle. Place it on sand bags and pull the bolt to see about where it will hit. You can tell if it’s going to be far off. Put a large target at 25 yards and fire a shot. You can either make an adjustment and count the clicks or just use Kentucky windage. Move the target to 50 and shoot again if it was hitting high and right by six inches or so just aim at the bottom left corner of the target. And fire a group. If it’s shooting sub1” at 50?move it to 100. If it’s shooting 2” at 50 let a proven shooter shoot a group with it and see what they get. If it still shoots bad for them it’s something with the rifle. You can put the borrowed scope back on your friends rifle. He shouldn’t have to fire more than a couple rounds to re zero it.
At this point we know it’s something to do with the rifle. At that point I would sell it. Even if it’s as similar or as cleaning up the crown you will not have confidence in the gun. It’s hard to shoot an animal with a weapon you don’t have confidence in v