Windage dead on at 100, 1moa right at 600????

Twisted

Twisted

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Jan 12, 2009
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NW Oregon
www.twistedfirearms.com
#1
I have had this problem with my rifle, Remington 700 SPS Tactical in .308. It is zeroed at 100 yards and does great (I know, its only 100 yards, I just use it to check my zero) but when I back up to 600 yards, dial up 15.xx moa or whatever, my poi is about 1 moa right. I get concerned so I move back up to 100 yards and its dead on.

It used to be about .5 moa off at 600 but then I went to a new stock and after zeroing it again it was just over a minute off.

I was told the scope could be twisted. I looked at it several ways and if anything it was twisted one direction just a hair so I twisted it the other, retorqued, rezeroed, and still a minute off at 600. If anything it should a minute off the other direction because I moved the scope in er of the opposite lean.

Is this just common? Am I missing something real simple. I even made sure my cross hairs were plumb and level the other night and still about 1 moa off in windage. Its really bugging me and I'd like to figure it out.
 
#4
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rob01</div><div class="ubbcode-body">Could just be the wind. </div></div>

I've thought that but I ask the guys shooting next to me if they are having to adjust for it and either they are not or we are all compensating the same, with me adjusting additional to the issue at hand. And usually we have little to no wind where we shoot.
 
#5
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body">There's a lot more stuff that comes into play @ 600 vs. 100.... </div></div>

Oh I understand that completely, just trying to understand what is causing this particular reaction so I can either fix it or understand why and how to compensate for it.
 
#6
Re: Windage dead on at 100, 1moa right at 600????

No such thing as little or no wind at 600 yards if you are outdoors.....

There's also the possibility that your reticle and erector aren't perfectly in line (canted reticle) or that your scope isn't perfectly plumb when you shoot. Its for a rifle to be canted just a c-hair. Without a plumb bob hanging at your target to verify your exactly vertical a little would do it.
 
#7
Re: Windage dead on at 100, 1moa right at 600????

I agree that it's more than likely the wind. I just ran my personal load through JBM Ballistics and it would only need about a 2 mph wind to blow the round 6" off the intended POI, that's not much.
 
#8
Re: Windage dead on at 100, 1moa right at 600????

If you are dialing 15+ moa at 600 you don't have the best wind bucking bullet. My relatively slow 168's only need a 2 mph wind somewhere along the way to be one moa of windage at 600.....
 
#10
Re: Windage dead on at 100, 1moa right at 600????

Hmmm, would it only need minimal cant to make it do that? I don't have access to another range at that distance so can't compare at another location. I don't know why I didn't think about this but shouldn't I be able to set up at 100 yards, hit my zero, then dial up 16moa or so and make sure the next shot is directly above the X? If it is canted it should throw the round an inch or so to the right. That would eliminate some of the wind aspect. Or am I wrong about that?

Thanks for the help guys, I'm still learning.
 
#11
Re: Windage dead on at 100, 1moa right at 600????

That may work. Or just record your data (including wind & lighting), then record it next time, and next time, etc and pretty soon you will know what's going on.

Your load post a couple weeks ago shows you shooting 175's under 2600fps......won't take much wind to have a 6" drift.

 
#12
Re: Windage dead on at 100, 1moa right at 600????

Spin Drift!
laugh.gif
 
#13
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">That may work. Or just record your data (including wind & lighting), then record it next time, and next time, etc and pretty soon you will know what's going on.

Your load post a couple weeks ago shows you shooting 175's under 2600fps......won't take much wind to have a 6" drift.

</div></div>

I should have mentioned I shoot this exact range once a week and it is consitant from week to week off in windage even with different winds. But you guys may be right and it could just be the wind. I may try the 100 yard test anyways just to see what comes of it.

And on a side not, I put about 14 rounds down the tube at 600 with the new load of 175's and the elevation was tits on every shot, just the swirling winds the other night causing some side to side action. I am pleased with the load right now. Wish it had a little more umph behind it but not bad for a 20" barrel.
 
#14
Re: Windage dead on at 100, 1moa right at 600????

go with the least complicated explination first..wind
you will comonly experience the same wind conditions when you go to the same range. Remember, you are shooting in the exact same terrain, in the exact same direction, every time. Winds usually come from one direction most places, most of the time. I wouldnt fret. Do this next time though, if the wind is slight or seemingly nonexistant, watch the mirage though your scope, and will soon see otherwise.
 
#15
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Spin Drift!
laugh.gif
</div></div>

Cannot believe it took this long for that to drop LOL...
 
#16
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Twisted</div><div class="ubbcode-body"> I don't know why I didn't think about this but shouldn't I be able to set up at 100 yards, hit my zero, then dial up 16moa or so and make sure the next shot is directly above the X? If it is canted it should throw the round an inch or so to the right. That would eliminate some of the wind aspect. Or am I wrong about that?
</div></div>

You're on the right track now. Are you using any kind of leveling device? You may be just canting the rifle. Get a piece of paper about 30" high and draw a straight line down the middle. Align the line on the target using a plumb bob on your target stand. Place a small aiming point at the bottom of the line, making sure the rifle is level and shoot a group at 100 yards and then dial up at least as many MOA as you are planning on stretching the scope out to and fire another group using the same aiming point. One note, watch it you get close to the end of the elevation travel because some scopes will not track well at the extreme ends of the travel. If the group doesn't follow the line the same then rotate the scope and try again. Make some kind of witness marks on the scope and one the rings so that you can keep up with how much you are moving the scope. This should take all the guess work out.

David
 
#17
Re: Windage dead on at 100, 1moa right at 600????

Probably a breeze between you and the target your not picking up.

Go out in the hills somewhere and shoot that same distance, then rotate 180 degrees and shoot at the same distance in that direction and see what happens.

Very, very seldom is it ever dead ass calm.
 
#19
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Stewart</div><div class="ubbcode-body">You might want to speak with Lowlight about "lunar drift". Were you shooting in the early morning or more towards the evening when the sun starts going down? </div></div>

It was about 6pm so not too late.
 
#20
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Twisted</div><div class="ubbcode-body">I have had this problem with my rifle, Remington 700 SPS Tactical in .308. It is zeroed at 100 yards and does great (I know, its only 100 yards, I just use it to check my zero) but when I back up to 600 yards, dial up 15.xx moa or whatever, my poi is about 1 moa right. I get concerned so I move back up to 100 yards and its dead on.</div></div>

Run a simple tracking test.

Put a large piece of paper at 100 yards. Draw a line on it perfectly plumb (use a level). Put an X, or a shoot-n-see or some type of aiming point at the bottom.

Shoot a round, dial up 5 or 10 MOA. Shoot another round.

Repeat the process for 20-30 MOA. You should have a trail of holes pretty much on the line. If they arc off to one side or the other, then your scope may be off. If they track right up the line, then it's just the wind.
 
#21
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Spin Drift!
laugh.gif
</div></div>

My bet-tad of wind to boot(not felt)

one search for it
http://www.snipercountry.com/HotTips/Spin_Drift.htm

one qoute
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Guys, I mentioned spin drift for the fun of it. A normally weighted and stabilized bullet travels nose down during descent of trajectory and normal spin drift occurs in the direction of the spin, ie right for right spun barrels. This drift would run about .25 moa at 1000. We use spin drift for the 168 because of the rounds tendency to fall nose high from being over stabilzed past 700. This drift runs about .5 moa at 800. This is farther than you should shoot that bullet. It is optimized for 600 yards or about 554 meters. </div></div>

http://en.wikipedia.org/wiki/Magnus_effect

partial qoute--see link above for lotsa stuff

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The Magnus effect is the phenomenon whereby a spinning object flying in a fluid creates a whirlpool of fluid around itself, and experiences a force perpendicular to the line of motion. The overall behaviour is similar to that around an aerofoil (see lift force) with a circulation which is generated by the mechanical rotation, rather than by aerofoil action.[1] In many ball sports, the Magnus effect is responsible for the curved motion of a spinning ball. The effect also affects spinning missiles, and is used in some flying machines.

German physicist Heinrich Magnus described the effect in 1852.[2] However, in 1672, Isaac Newton had described it and correctly inferred the cause after observing tennis players in his Cambridge college.[3][4] In 1742, Benjamin Robins (1707-1751), a British artillery engineer, explained deviations in the trajectories of musket balls in terms of the Magnus effect.[5][6]</div></div>
 
#22
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">
Run a simple tracking test.

Put a large piece of paper at 100 yards. Draw a line on it perfectly plumb (use a level). Put an X, or a shoot-n-see or some type of aiming point at the bottom.

Shoot a round, dial up 5 or 10 MOA. Shoot another round.

Repeat the process for 20-30 MOA. You should have a trail of holes pretty much on the line. If they arc off to one side or the other, then your scope may be off. If they track right up the line, then it's just the wind.</div></div>

Good advice. I do that with every scope I own after mounting and zeroing. Here's a pic of my chart I made on some graph paper. The dark in the center is to check the reticle mil spacing, the left is to make sure the reticle is perfectly vertical and the right is to check tracking. This is the MOA version as I have a mil one too. You can see the bullet holes covered with light masking tape on the right that start to veer off to the right? That is a quickly mounted scope which wasn't mounted true and what you may see if you have a internal/tracking problem or mounting problem. You dial the elevation on the scope and keep your aiming point at the bottom zero mark. I put a MOA box every 5 MOA starting at 10 and going to 40 MOA.
P1010001.jpg
 
#23
Re: Windage dead on at 100, 1moa right at 600????

If it's consistent, it may be cant; but actually it doesn't matter if adjusting in a little cant can fix the problem. Using one nono to counter another problem is fine, as long as it actually works.

Greg
 
#24
Re: Windage dead on at 100, 1moa right at 600????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Twisted</div><div class="ubbcode-body">I have had this problem with my rifle, Remington 700 SPS Tactical in .308. It is zeroed at 100 yards and does great (I know, its only 100 yards, I just use it to check my zero) but when I back up to 600 yards, dial up 15.xx moa or whatever, my poi is about 1 moa right. I get concerned so I move back up to 100 yards and its dead on.

It used to be about .5 moa off at 600 but then I went to a new stock and after zeroing it again it was just over a minute off.

I was told the scope could be twisted. I looked at it several ways and if anything it was twisted one direction just a hair so I twisted it the other, retorqued, rezeroed, and still a minute off at 600. If anything it should a minute off the other direction because I moved the scope in er of the opposite lean.

Is this just common? Am I missing something real simple. I even made sure my cross hairs were plumb and level the other night and still about 1 moa off in windage. Its really bugging me and I'd like to figure it out. </div></div>

I chased POI right for months. I was told and always thought it was the wind or me which could be but...it was always right and logged to always dope for POI right as I stretched it out.

I hung a 3mm thick black pcord with heavy weight on the end on a 48" tall cardboard target at 100 yards. I could tell by the top mildot, I had to strain my eye, my scope was ever so slightly twisted when my ACD was bubbled level. I put a shoot-n-c paster dot at the bottom of the cardboard cut center by the pcord. At 36moa up I placed another paster cut center by the pcord.

Shot 3 rounds at the lower dot, cut center. Doped in 36moa which is 1000 yards and I was well over 3" to the right. Back to 100 cut center and back to 36moa with same results. So I twisted my scope so the top mildot lined up with the string, shot and now I was just about 1" or so still to the right. Using a #2 pencil mark on the rings and scope, rotated scope slightly until I cut center 100 and cut center doped 36moa. Walked target out and by golly, my group on a 5" shoot-n-c centered vertically at 350 yards.

No POI right since, hope this helps and good luck!
 
#27
Re: Windage dead on at 100, 1moa right at 600????

LOL Chad as soon as I seen topic I was like I am gonna strat the drama and say Spin Drift just to perk up some eyes LOL.

Probably some light wind or even the way you are driving the weapon. Those small errors are getting magnified as you go deeper.
 
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