Zeroing question for 100yds

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Black Jack

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Is it possible for a rifle with a stock scope rail to not be able to zero at 100 yds. If i had a 20 moa rail maybe it would be normal but is it possible for a stock setup? I shoot a Remington 700 in 308 with a Bushnell Elite 4200 6x24. Velocity is in the range of 2780fps. I read that sometimes the scope can "bind" inside so I cranked it all the way both directions and counted to bring it back to the middle. From then, started shooting to try to zero it for 100yds. I run out of adjustment before i can get to my POI for 100yds. So I zeroed it for 200 yds instead. I remember when I was reloading with a velocity in the 2400fps I had no problems zeroing for 100yds. What am I missing?? Or maybe it's just what it is and live with it? Tks

Pat

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Black Jack said:
Is it possible for a rifle with a stock scope rail to not be able to zero at 100 yds. If i had a 20 moa rail maybe it would be normal but is it possible for a stock setup? I shoot a Remington 700 in 308 with a Bushnell Elite 4200 6x24. Velocity is in the range of 2780fps. I read that sometimes the scope can "bind" inside so I cranked it all the way both directions and counted to bring it back to the middle. From then, started shooting to try to zero it for 100yds. I run out of adjustment before i can get to my POI for 100yds. So I zeroed it for 200 yds instead. I remember when I was reloading with a velocity in the 2400fps I had no problems zeroing for 100yds. What am I missing?? Or maybe it's just what it is and live with it? Tks

Pat
Click to expand...

Something isn't quite right with that. I suggest remounting the scope and using a Bushnell grid bore sighter to get your cross hairs back to "center" and your shots "on paper",then,go back to the range. It should take less than 3 shots to zero your scope. FWIW,I zero my big game scopes (Bushnell TrophyII) at 1" high at 100M,putting the bench rest shots dead center 1MOA at 200M. Once you have it set,re-install your bore sighter and make a note of the cross hair position on the grid. You can then quickly re-check your "zero" at any time without firing a shot which is really handy if you've been traveling with your rifle(s).
 
I see you have two piece bases. You're 100% sure nothing's loose on there??

You're right, with a 0MOA mount, there should be no problem hitting zero at 100.
 
Yes sir, nothing loose. Everything was torqued. I suspected something loose so I took everything apart and remounted everything back up. Couldn't get the 100 yds zero but very consistent at 200 for grouping.
 
Me thinks there is something wrong. It might be an optical illusion, but that scope doesn't look level. And the one ring looks a little crooked. I'd verify my bases and rings. Make sure you've got the right ones on. I've seen situations where the wrong # base was used and it all looks okay, but it's just a little higher or lower than the other one.
 
Spend 50$ and get a 1 piece base.....

Having said that, if it zeroes at 200 regularly, still might be something in the scope. When you ran all the clicks out, did it go as far as the specs say it should? Is there a zero stop making your life difficult??
 
Try spreading the rings out some , you may have them way too close together and get a 1 piece rail.

That close together and tightening them there may cause issues internally?

You can also shim the ring if you need to.
 
Yes it did go the same amount of clicks both ways. Then recounted the clicks to bring it back to it's "original" zero meaning in the center of both adjustments. No zero stop on this scope. The only difference I can confirm is the difference in my loads. I did a ladder test and loaded on the second node. 46.1gr of Varget compare to the 39gr of H4895 of before. Shooting the same bullets. Hornady Match 168gr.
 
Can you be 100 % certain that your scope rings are not 20 or even 40moa rings? You can try swapping them front to back just to be sure. Something is not right somewhere. it's just a matter of figuring it out. You can also look at your scope mounts and measure them to ensure they are equal height.
 
If I'm not mistaken that scope only has about 26 moa of vertical adjustment ( compared to and average of 60-80 on most modern scopes with a 1inch tube)may not be enough to zero at 100, had the same problem with my buddys a bolt and a 6-24x40 Bushnell 4200, had to shim the front ring/base to get it to zero. It was shooting about 8 inches high when you had it dialed all the way to the bottom.
 
It appears that the rear base is thicker than the front base and the front ring appears to be to far back and partially over the ejection port.

There will be lots of whip in that set up with a large portion of the scope unsupported.

Could the bases be backwards, the rear should be the front base and vice?
 
I will check about the bases for sure but I believe it's the angle of the picture. Both base are more or less flush with the port of the action. Do not have the rifle with me, but will check tomorrow.
 
Question: Did you paint everything separate and then put together after or paint it all as one piece?

Rem 700 bases are not equal thickness due to the design of the action.

You can turn your front base around if you wish. Your scope has a long tube and it will add support by doing so.

Be cautious adding shims. By placing shims in, your rings will no longer be in alignment vertically or may not be now. With your scope rings close together as they are, small shim will make larger changes.

You can switch bases out for a 1-piece rail and bed it if it floats OR get Burris Signature rings and the necessary inserts to correct the problem.
 
The difference between 100 and 200 yard zero is about 2 moa, so swapping rings around, or different rings might do the trick. You are ever so slightly off.
A laser boresighter is useful for this kind of business.
 
Shooter ----/ said:
Be cautious adding shims. By placing shims in, your rings will no longer be in alignment vertically or may not be now.
Click to expand...

Shims placed in the rings reduces the ring diameter that was meant to fit the scope... 1 inch scope tube and a ring smaller than 1 inch isn't a good combination. Never shim inside a ring.
 
I have never had a problem with shimming a ring or base when I needed adjustment. I do agree it takes less competency to shim a base than a ring due to incompetent people and over torquing of a shimmed ring onto the scope tube.

Maybe a set of Burris Zee rings with the assorted shims is a solution.
 
Think about the logistics of shimming inside a ring... The scope tube is made to a specific diameter and the ring is made to fit that diameter... lets say it is a one inch tube and one inch rings... add a 20 thou shim to the bottom inside of a ring and that 20 thou is going to compress into the bottom of the scope tube. It may raise the tube slightly but it is also distorting the tube. I have seen many scopes tubes with a distortion on the bottom of the tube. Why would anyone want to do this?
 
guntech said:
Think about the logistics of shimming inside a ring... The scope tube is made to a specific diameter and the ring is made to fit that diameter... lets say it is a one inch tube and one inch rings... add a 20 thou shim to the bottom inside of a ring and that 20 thou is going to compress into the bottom of the scope tube. It may raise the tube slightly but it is also distorting the tube. I have seen many scopes tubes with a distortion on the bottom of the tube. Why would anyone want to do this?
Click to expand...

I agree that it has the potential to damage.

I have shimmed with no issues, however I was careful. In fact I just pulled a scope from an XCR-L to put on a Remy 700 and removed a shim in the rear ring.

Why? To simply solve a problem without removing everything again. Easy to slip an aluminium shim in a rear ring than start over in a range setting vs a shop setting. Likely the same similar concept behind Burris shims in their Zee rings.
 
I had the exact same issue with my Rem 700 , using 2 pc rings with a Vortex optic. Spoke to the guys at Reliable, mentioned to try and shim rear mount before swapping out rings/bases. Small layer of shim material and had no issues zeroing out optic.

I'm my case it was Leopold rings/Bases.

I used a piece of clear thin plastic from packaging.
 
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