Gun in bag set up

[chet]

I am just about done with my new BR rifle, I made the BR stock from a block of hardwood, so I set the gun on my shooting table in my garage today, mount the scope ect, if I need to make adjustments to the bottom of the stock it can be done easily, with the gun up against the stop on the front rest, I am set on the target bull, If I pull the rifle back approx 3' I look thru the scope again and the crosshairs are off to the left approx 1/8' at 50yds, I did this a few times up to the stop and back again, it is always about 1/8' is this something that is crucial to accurate shooting, I imagine If I sand the rear stock area, I can correct this. any thoughts on this.

Chet

 

[medicineman]

It would sound like the centerline of the butt is angled to the centerline of the forend. One way to check it, I have found is to 'box gauge' it. When ever I build a new pattern, it has to be symetrical from side to side. In effect, you build a box from some solid,flat hardwood or a good flat piece of 3/4' plywood. If you are building a 3' wide BR stock, the box should be 3' wide on the inside and high enough to cover the total hieght of the stock. What you are going to do is place the stock in the box that is tight to the stock on both sides and gauge the side of the stock from the inside of the box to the center line. I have made sanding templates to sand the butt going from the inside of the box. The template will sand the same amount off each side by reversing it.
Or it could be the rear bag is slighly out of square with the butt. This will cause the butt to drift some when the butt slides lower in the rear bag because of where it contacts the ears.
I used to have the same problem until another shooter observed me shooting and pointed out that when I cycled the bolt, I actually disturbed the rear bag somewhat. I then began to double check the rear bag before every shot and it helped tremendously with horizonal.