I had a gentlemen PM me and said that I might have the same problem. I know that there are some strange vibrations going on with that mag tube and hanger only a couple of inches from the barrel.
I am hoping it is like my Pre-64 winchester 70. The barrel has almost no freefloating, and there is a big ol screw that secures the stock to the barrel about halfway down. With everything I know about firearms and accuracy, my model 70 should not be a shooter--It sure does shoot!
I am hoping that the mag tube will not be an issue. If it does effect accuracy, I am going to find a way to hang that sucker in a way that wont degrade accuracy.
My main issue with my "experiment" is not having enough money right now to buy the scope that I want. The scope mount and rings are already going to be in the 70 dollar range. Once the scope gets here, I will start a new post with my initial groups and load data. Then I will start knocking down accuracy robbing variables. It should be a pretty fun experiment.
Here is what I would love to put on this gun: Leupold VX-3L 4.5-14x56mm Long Range Riflescope
BUt, 900 bucks is alot of money to spend on a scope--it might as well be a million right now. I have a feeling it will probably be after x-mas before this happens. For now, I'll probably rob a 3x12 redfield off another gun. However, it is really cold outside, so I don't know how much shooting will happen for a while.