Question about windage change at 300 with no wind at all

[6.5guy]

I have a problem I have a nightforce atacr 7x35 and love it but for some reason I have leveled this scope on a plumb line and with levels but for some reason at 100 my windage is right on and I get to just 300 and it goes to the right every time and I was gonna c wat y’all thought I should do or wat I’m doing wrong should I say thanks

 

[std7mag]

Adjust for bullet spin?

 

[JSH]

Did you adjust for 300, then see where you are at 100?
Slight adjustment @300 may not even show @100.
Dunno what cartridge, but have seen crazy stuff when bullets go from supersonic to transonic. Then restabilze again, but be wayyyy off of original impact area. This was really noticeable with cast when I first saw it happen, then got to talking to others I shoot with and came to the conclusion it was going on with some jacketed loads.

 

[gunsandgunsmithing]

I'd still bet on wind. A 1-3mph wind is barely detectable on the skin, but the bullet feels it and truly calm wind is pretty rare to have for long enough to do much testing. Foggy mornings are a good time, if you can see the target.

Smoke goes straight up in a true calm. Anything else is a wind that will act on the bullet.

 

[6.5guy]

Well if it’s the wind it must b pulling the bullet into the wind Because the slight breeze that was blowing wouldn even read on my kestrel and was coming from right to left and the bullet is shooting to the right so that don’t make since for it to b the wind and it’s. 6 creedmoor I have shot alot and never had a problem with wind and if I dial it will effect the 100 yard zero as well

 

[gunsandgunsmithing]

Well if it’s the wind it must b pulling the bullet into the wind Because the slight breeze that was blowing wouldn even read on my kestrel and was coming from right to left and the bullet is shooting to the right so that don’t make since for it to b the wind and it’s. 6 creedmoor I have shot alot and never had a problem with wind and if I dial it will effect the 100 yard zero as well

Wind does some strange things and I seldom get the near and far flags to agree. It's common to discount how much effect wind has. Get some surveyor tape and some wire rods to set out. It'll tell you enough to at least know when not to shoot.

 

[243winxb]

A little right is normal.

A lot right or even left is an "Off Axis" problem.

 

[6.5guy]

I got wind flags up they hang over the backers And the is no movement on the flags and wat do u mean by off axis? I just thank I don’t have the reticle level and when I dial it is making it do that but I can’t find a good way to level it really

 

[243winxb]

Off axis- the scope is not sitting centered over top of the bore.

Or the windage adjustment is cranked almost fully to the right or left.

Scopes should have there adjustments centered, bore sight & shim to get close to zero.
Mounts that are adjustable should help.

When i have a 300 yard zero, my bullet impact is about 1/2" left of center @ 100 yards. I think normal for a right hand twist 243 Win. barrel.

 

[Chuckhunter]

Take a target that is 13"X21" like a two hundred yd. IBS score target and turn it backwards, hang it with a carpenters level, then draw a vertical line down the center with the level. Put a small target dot a few inches from the bottom of the target right in the middle of the line. shoot to hit dead center of the dot then click up approx. 6 clicks (.250 min. scope) shoot a shot then click up approx. 14 clicks more and shoot another shot and you can continue that until you get to the top of the target. If your shots are intersecting the line or within a bullet hole of the line, your scope is good if they walk left or right at a small diagonal you'll have to make the necessary adjustment until it walks straight up. Once you're certain that it's true what you'll be seeing at 300 and beyond will be condition related. Use a scope level if you have on, if not make sure your rifle is level in the rest with a small level on your scope's elevation turret. This method will drastically reduce 300yd. condition related error.

 

[SG4247]

I just make this with a square and cardboard.

Then hang it at 100 yards with a level.

Zero the rifle at the Vert/Horiz intersection.

Turn the scope up 10 MOA and hold the same intersection and shoot.

This tells me the scope is mounted right and tracks well enough for windage at 500-600 yard shooting.

 

[6.5guy]

I have some targets that have moa marked on them For scope trackin I just need to put it up level and check it I guess

 

[gunsandgunsmithing]

I got wind flags up they hang over the backers And the is no movement on the flags and wat do u mean by off axis? I just thank I don’t have the reticle level and when I dial it is making it do that but I can’t find a good way to level it really

You might hang a plumb bob at the target and level the rifle in the rest. Align the vertical crosshair to the plumb line.

 

[gunsandgunsmithing]

I have some targets that have moa marked on them For scope trackin I just need to put it up level and check it I guess

That can work too, so long as the gun is level...or as level as it is when shooting it.

 

[JEFFPPC]

I got wind flags up they hang over the backers And the is no movement on the flags and wat do u mean by off axis? I just thank I don’t have the reticle level and when I dial it is making it do that but I can’t find a good way to level it really

If you dont have some windflags between you and your 300 yd target your wasting your time. If you have a true no wind no mirage condition and a very accurate rifle at three hundred yds you will see a click or 2 difference as the right hand spin of your rifling affects the bullet flight.

 

[gunsandgunsmithing]

If you dont have some windflags between you and your 300 yd target your wasting your time. If you have a true no wind no mirage condition and a very accurate rifle at three hundred yds you will see a click or 2 difference as the right hand spin of your rifling affects the bullet flight.

That's likely true but my adjustments are almost always for wind. The small difference you're referring to just gets lost in the noise, for me.

i.e.--A .514bc bullet at 3000fps has .5 drift at 300 yards in a 1mph wind.

 

[6.5guy]

There is wind flags on every set of targets

 

[Ned Ludd]

I may have missed it, but when the rifle is zeroed at 100 yd, exactly how far to the right will the impacts be at 300 yd? Also, are they at the expected elevation on the target? A canted scope basically turns windage into elevation, and vice versa. The results of a right-canted scope should be the POI moves both right and down. However, a scope has to be canted pretty badly to cause a marked shift right+drop at only 300 yd. I would think you would easily be able to tell the reticle is canted by just looking through the scope.

Alternatively, you can use a ballistic calculator such as JBM Ballistics to estimate either spin drift or wind drift: https://www.jbmballistics.com/cgi-bin/jbmtraj_drift-5.1.cgi. If you carefully consider the size of the shift in POI at 300 yds you've been observing, it may possible to rule some possible cause(s) out simply because they do not typically produce the same magnitude of effect, which is why I asked, "How far right?".

 

[SG4247]

I just make this with a square and cardboard.

Then hang it at 100 yards with a level.

Zero the rifle at the Vert/Horiz intersection.

Turn the scope up 10 MOA and hold the same intersection and shoot.

This tells me the scope is mounted right and tracks well enough for windage at 500-600 yard shooting.

Let me add, in order for this method to work, you want a pretty good rifle and load, roughly 1/2 MOA. So, if the rig prints 1.5” group at 100, this wont tell you much.

 

[6.5guy]

It is impacting roughly 1moa to the right at 300 witch is 3in and the rifle will shoot into the same hole at 100 yards I’m not sure wat it measures as I never mesure it it is very capable of shooting less than half moa and at 300 it just stacks them on top of each other but they r just to the right I can adjust it to make up for it but I do not want to have to do that when there is no need for it thanks guys