Dead on at 100yds 4inches right at 400yds

[Laguna Freak]

Maybe I missed it but I didn't see where you said scope base(s) snd thus tube is "absolutely centered" over the action.

 

[JakeC]

So far on every suggestion you have indicated you have it 'covered', which eliminates the rifle. My suggestion is it is either wind or hindering shooting techniques which becomes more pronounced at longer distances. Try having someone else shoot the rifle or use a different shooting position (bench vs prone) for validation.

I agree, that should help winnow some things out. That is a very, very steady wind to be what's causing that drift in an OK group, but you've covered a lot of other bases. I'd say try it off a sled, a friend, sandbags, and sticks to see what happens. Also, how much recoil and velocity are we looking at? I believe you're right in being puzzled, I just can't picture what kind of gun is firing this.

 

[David Emerson]

No barrel is straight. It could be that your barrel is indexed with the bend so that the muzzle is to the right.

 

[remingtonman_25_06]

Thats why I zero my LR rifles at 300 yards...

 

[buzzyb]

The gun is a custom built 300 win mag. Deviant action, proof carbon barrel,Nightforce ATACR,seekins rings. I am shooting Berger 215, 76 gr H-1000 ADG brass, at 2976fps

 

[338 dude]

The gun is a custom built 300 win mag. Deviant action, proof carbon barrel,Nightforce ATACR,seekins rings. I am shooting Berger 215, 76 gr H-1000 ADG brass, at 2976fps

Man that should be one Good shooting rifle It's got to be some bad data in your ballistics program

 

[243winxb]

300 win mag

What kind of rest? Getting just perfect on the bags when going to a different yardage can change things.
How the rifle recoils may be something to look at.

I have seen shooters get different bullet impack on target using this type of rest. When compared to bags.

 

[buzzyb]

Atlas bipod and wedge rear bag

 

[243winxb]

bipod

Might try something like this internet photo? Its close to how i set up. Just something to try.

 

[buzzyb]

Iam going to try just bags today see if that makes a difference

 

[Alex Wheeler]

You said no wind, do you have some wind flags, surveyors tape, ext down range to watch? Many times there may be no wind where you are but down range there is.

 

[buzzyb]

No I don't . How much will wind effect the poi at 400yds

 

[22Kreedmire]

with my 300wm and 215's at 2870 i show .25" drift to the right (spin drift) at 400 no wind 5mph left to right give little over 3" drift according to kestrel

 

[Alex Wheeler]

A lot more than canting your scope/rifle a few degrees.