shifting zero

[44mag1]

Im asking this for my cousin, he has a remington 700 243 with a burris 3x9 scope. He sights the gun in, goes back to the range a week later and the POI is 3 inches off. Crazy thing is it is different every time. sometimes the group is high, sometimes left, right,low. All the obvious things have been checked,mounts are tight rings are tight. I wonder if its the wood stock warping. The barrel is floated. This gun shoots 1 inch groups every time.
Any thoughts.

[DLCTEX]

Change the scope and see if it stops the shift. If it does then you can look for harder to find problems.

[44mag1]

This is the second scope he's had on the rifle, both scopes, same problem.

[EOD3]

Does he pull the action out of the stock to clean it?

Is the barrel lug TIGHT in the action?

Same ammo every time?

Shift in the gravitational constant of the universe?

[oneokie]

Is the action glass bedded in the stock? The kind of changes you mention sound like the action is loose in the stock. Are the action screws tight? Does the barrel channel have the pressure point bump? or has it been removed?

[376Steyr]

Does he bring his own sandbags to the range? I've seen "sandbags" at public ranges that are more like chunks of concrete. Maybe he rests the forearm on a soft sandbag one week, a rock-hard one the next.

[Larry Gibson]

How does he transport the rifle to the range?

I ask because Rifles hanging in gun racks or vibrating around in cases on PU beds can be hell on scopes by shifting zeroes as described.

Assuming the same ammo/load is used and he uses good shooting technique(?).

Larry Gibson

[leadman]

I'm with Larry's last question there. Maybe you should shoot the last rounds thru the rifle at a range session and the first ones thru the next rang session. Will tell you if he is changing something in his technique.