Windage troubles at long range

[model70fan]

I am having problems with my 7mm STW shooting 6 inches right at long ranges. Ive shot it at 400, 500,600,700 yards and it keeps shooting the same 6 right. Ive shot it again at 100 and 200 and 300 and it is right on the money. im shooting 180 berger VLD bullets at 2914fps. The gun is shooting really good groups out there just six inches right and on calm days. Scope is a markV 8.5-25 leupold, sitting on a krieger barrel and pre64 model 70 Winchester action. any help would be apprciated.

 

[Broz]

Are you dialing up or hold over? I will assume dialing. Do you have a bubble level and have you leveled it to your reticle path? Past 700 you should be getting some spin drift as well. Probably about 1/2 moa at 1000 for SD.

Jeff

 

[model70fan]

I am dialing up with leupold custom turret and the elevation is fine and the groups are fine its just printing 6 inches right consistantly with 2 different people shooting it.

 

[Broz]

I am dialing up with leupold custom turret and the elevation is fine and the groups are fine its just printing 6 inches right consistantly with 2 different people shooting it.

If you are dialing then I ask again if you have a level and have you used a proceedure to level your scope ?

If you have not I will sugges you do. As I feel you could have a canted scope and your reticle path is taking you right as you crank in elevation.

Jeff

 

[model70fan]

I have not leveled the scope and will try it. Thanks

 

[Broz]

I have not leveled the scope and will try it. Thanks

I think that is a good place to start. Get a level on the rail or tube and check it at 100 yards with a plum line. There are many good threads on here to discribe the process. Then after you have confirmed all is true to each other keep an eye on that level before braking the shot.

Also be aware of any wind even down range.

Jeff

 

[WildRose]

Ive shot it at 400, 500,600,700 yards and it keeps shooting the same 6 right.

Leveling the scope won't hurt a thing, and may help a little but if you are consistently 6" off at different ranges I'm going to lean more towards shooter error being the primary cause.

My bet would be that you are anticipating the recoil and leaning forward as you squeeze the trigger which for a right handed shooter would most often result in being off to the left.

 

[model70fan]

The gun is off to the right and with 2 different shooters it is doing the same thing

 

[WildRose]

The gun is off to the right and with 2 different shooters it is doing the same thing

Well if the problem is either with the gun or the scope the error should increase proportionally to the range.

If you were off 6" at 500yds, 9" at 750 and 12" at 1000yds, it would make sense that it's a mechanical problem of some sort.

But to be consistently off 6" at 500, 600, 700, etc points to something else being the issue or it's the cumulative effect of a series of minor errors somewhere, but if it's purely a mechanical problem it should increase proportionally to the increase in range.

 

[Broz]

Well, I probably read to much into it But consider this guys.

The OP is stating 6" at 500, 600, 700 etc. Ok, 6"... But even a 3/4 moa rifle/shooter combo at these distances the group would be more than 1/2 of the error we are looking for. So, I will stay with the level theory and cranking up with a sight picture of non level ground causing both shooters to cant due to an optical illusion. Or crooked target.

Jeff

 

[shortpants]

I believe Broz is correct because the same thing happend to me. Go buy a scope leveling device (I used a Level-Level-Level). Once your scope is level set up a target at your zero yardage (mine is 100) and draw a vertical line about 36" in the center of your target (plain old white paper will do). The vertical line must be perfectly plum after setting it up at your zero range so take a marker and plumb line or level with you to the range. Put an aiming point at the bottom of your line and zero the rifle at the aiming point. Once you are confident that your zero is perfect just dial up your scope one full revolution BUT DON'T FORGET TO TURN IT BACK TO ZERO AFTER THIS TEST!!! With your target still at your zero range and your turret cranked up a full revolution shoot another group. It should impact towards the top of your vertical line you drew on the target. You have to shoot consistent if you expect accurate results. This is a great time to check how accurate your vertical corrections are on your scope. Measure the distance between groups and see if the distance matches what you dialed. I believe this test will solve your problem but remember you have to shoot straight in this or any shooting test to get good results. Good luck!

 

[WildRose]

Along with checking the scope/rifle level/perpendicular relationship you might want to also look into an anti-can't level for your rifle/scope.

If you have everything set up perfectly on the rifle/scope combo but have the slightest can't in how you are holding it can create a large error down range.

Here's a few:

Brownells Search : Optics & Mounting : Scope Accessories : Scope Anti-Cant Devices - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools - BROWNELLS

This is another very good one:

http://www.mountsplus.com/mm5/merchant.mvc?Store_Code=MSP&Screen=PROD&Product_code=HV-ASLI

Not many shooters have a good enough eye for plumb/perpendicular to really guage it closely without a bubble level.

Simply a one mil error at a thousand yards is nearly 3' in windage error.

 

[Bravo 4]

Along with checking the scope/rifle level/perpendicular relationship you might want to also look into an anti-can't level for your rifle/scope.http://

While you're at it, might as well check if the reticle is canted inside the scope.

 

[WildRose]

While you're at it, might as well check if the reticle is canted inside the scope.

Well aligning the scope to plumb and using one of the anti cant levels along with a level on top of the scope should solve that equation easily.