Ha! Yep, I definitely had accuracy problems. So the Mosin Nagants have free floating barrels, which is supposed to improve accuracy. When you install the the barrel into the Archangel stock you only use the two screws you took out of the wood stock. One is on top where the bolt slides into the chamber and the other is underneath into a mount right before the bbl starts. This didn't work for me so Archangel provides a tensioner in every package, but specifically state it shouldn't be needed with the Mosin. It's interesting though because they provide it anyway.
The tensioner is a small rectangle box that has a hex screw on one end. There is a slot mid way down the Archange stock where this tensioner slides in. Once the tensioner is in place you install the barrel in the stock over the tensioner. The screw has a cutout in the stock so you can see it on the underside of the stock and it can be turned to expand the tensioner. With the screw all the way down on the tensioner it does not touch the barrel, but as you turn the screw the tensioner expands putting pressure on the barrel so it's no longer free floating.
Because Archangel said it wasn't used with the Mosin I didn't even install it before I mounted the barrel. At the range I took it apart, mounted the tensioner and then put the rifle back together. As I turned the screw applying more tension against the barrel, my groups closed up. I put a good amount of tension against the barrel to get it to function accurately. I guess each barrel is different so this happens to work for mine.
Would have to think there is a way to do this with a normal Mosin in it's original stock. Might help with your accuracy as well.