Never had this problem before.

So Today I bought an actual 20 MOA base and a set of low rings. Correct me if I am wrong, but the scope sitting higher above the bore will use some of my elevation range to zero. So moving the scope .46 inches closer to the bore should result in me having to dial down to zero as compared to the higher rings. Am I not thinking correctly?
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I'm guessing the effect of scope height in overall elevation use is very negligible, if any at all (except maybe at true point-blank distances).
 
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kilotanker22 said:
I am also not looking to burn through hundreds of rounds of ammunition before looking at my hardware. There is obviously a problem there somewhere.
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I have a Savage tactical that is a mystery like that. 20 MOA rail and Bushnell 6500. With a 100 yard zero, its 6" high at 400. I gave up trying to figure out why.
 
I don't know for sure, but this is how I see it. When most people think of how scope height affects trajectory they think of it in relation to how the bullet crosses the line of sight for a particular zero. Once I am zeroed the scope height changing wouldn't affect the trajectory of the bullet all that much.

What I am talking about is the height of the scope above the bore affecting the amount of elevation needed to zero the rifle in the first place. Disregarding MPBR and bullet trajectory outside of a single distance. Assuming that the bore axis and the optical center of the scope are parallel to each other. Then the height of the scope will have a direct impact on the angle at which the bore will be pointed to meet the line of sight for a zero at a specific range.

So assuming that the angle between the bore axis and line of sight does not change moving the reticle down will move your point of impact up regardless of how that reticle is moved. Moving the entire scope down also moves the reticle down.

So it is my belief that by moving the scope closer to the bore and adding the angle from the 20MOA base should solve my problem.
 
44 AMP said:
Are you sure??

What I mean is, how do you know you only have 15MOA left? Are you certain your scope was "center" of its adjustment range before you started shooting?

Try this, run the scope adjustment all the way to the stop. Then run it to the other stop, keeping track of the clicks. See if that matches the stated range of adjustment in the scope. Using # of clicks move the crosshairs to the middle of the adjustment range. (if you can boresight at this point, do so) Then fire a few rounds to see where things hit, compared to where you aim.

If you have a "conventional" base, mount that and your scope and shoot and see what the results are. You have several variables here, rifle, mounts and scope. First thing you need to do is find out which one is doing what....
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I know that I only have 15 MOA of up adjustment left, because I counted the clicks until the scope stopped at the top of the adjustment.

The scopes internal adjustment is just fine I did check that. All of the components are fine Measured this morning.

I will install the new base and low rings tonight and then go to the range either tomorrow or Saturday and test my theory.
 
So it is my belief that by moving the scope closer to the bore and adding the angle from the 20MOA base should solve my problem.
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Maybe, but since the measurement difference is likely only an inch or so (and that's assuming your objective bell allows it) I don't see how that significantly changes the MOA dial-up range of your scope (assuming your base angle remains constant). I could be wrong though (have been many times ;) ).
 
stagpanther said:
Maybe, but since the measurement difference is likely only an inch or so (and that's assuming your objective bell allows it) I don't see how that significantly changes the MOA dial-up range of your scope (assuming your base angle remains constant). I could be wrong though (have been many times ;) ).
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Like I said. I might be wrong as well. It makes sense to my mind though...

I called Savage and let them know that the base that came with the rifle is in fact a 0MOA base instead of the 20MOA base itwas advertised to come with. They are sending me a new 20MOA base
 
what cartridge is this? Savages--while fantastic value rifles--are pretty notorious for arriving NIB with loose bases and receiver screws.
 
Two points to ponder........

* Setting the elevation and windage adjustments midpoint in their mechanical range does not center the inside tube and optics on the scope's optical axis which is the center of the outer tube the rings hold, and the centers of the eyepiece and objective lenses. There's typically more clicks available up and right when that inner tube is centered in the outer tube. The two V block method is best, the mirror method's a close second.

* Both front and rear rings must be the same height from bottom flat to scope tube.

Therefore, if elevation adjustment range is wrong, the base or barrel is not aligned to the receiver axis correctly.
 
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I have never even thought of that.

I got the new 20MOA Base, low rings and the scope mounted up tonight. My height above the bore is 1.74" now. I will try to test it tomorrow
 
stagpanther said:
That's assuming the bore axis and receiver axis are one in the same?
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Yes.

Easily seen with a mechanically zeroed scope in standard rings on standard bases and a collimator in the barrel muzzle. In extreme instances, visually bore sighting reveals the error.

After getting the installed scope zeroed for some range, the bore axis (line of fire) doesn't point to a place on target above the point of aim equal to the bullet's drop plus sight height above the bore center. That happens after rifle recoil moves the bore axis while the bullet moves in it to that place as bullets goes out the muzzle.
 
Yep. I have a mod 70 264 win mag that is extremely out of line. You cant zero it without "Redfield" windage adjustable bases. Bore sighted at 100 is over 10" right.
Having said that, its one of the most accurate light weight rifles I have ever seen. I believe it has a combination of factors going on. Bent barrel and centerline of action not square.
 
It would be nice if scope's instructions included the amount of LOS adjustments from the mechanical limits down and left to optical zero wherein the inside erector tube is centered in the main tube the mounting rings clamp onto.

That's easily done on the production line when the scope's put in an optical collimator and those knobs are set to put the reticle on the collimator reference. I built one with a 30" long 3" pipe with two sets of scope rings, bases and an old Weaver K2.5 scope twisted 45 degrees without an eyepiece at one end of the pipe pointed towards the other end where the complete scope is put in the other set of rings to view the "X" reticle in the K2.5 illuminated by a small flashlight in it's back end.
 
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reynolds357 said:
Yep. I have a mod 70 264 win mag that is extremely out of line. You cant zero it without "Redfield" windage adjustable bases. Bore sighted at 100 is over 10" right.
Having said that, its one of the most accurate light weight rifles I have ever seen. I believe it has a combination of factors going on. Bent barrel and centerline of action not square.
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What's over 10 inches right?

Most common cause is not a bent barrel, but the receiver barrel tenon's threads are crooked to the receiver axis its threaded holes have to attach scope ring bases in.

If the threads are on axis but the receiver face is not square with them, the straight bore axis is crooked to the receiver. This could be fixed adding only $25 to the retail price.
 
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At 100 yards, the rifle shoots 10" right of bore sight.
When I re-barrel it, I will square the action. I wont re-barrel it until I shoot it out because it shoots too good now to mess with. The barrel is definitely bent. The action is definitely out of square, but not bad.
 
Most, if not all, of that 10 inches can be caused by the bore axis swinging right during barrel time if you're right handed.

I'm right handed and all my rifles shoot to the right of bore sight. Moreso with lightweight sporter in 30 caliber magnums.

Remember that a bent barrel boresight involves the bore axis at the muzzle. A bent barrel is best bore sighted with a collimator that eliminates all but the front 2 inches of the barrel.
 
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Bart B. said:
Most, if not all, of that 10 inches can be caused by the bore axis swinging right during barrel time if you're right handed.

I'm right handed and all my rifles shoot to the right of bore sight. Moreso with lightweight sporter in 30 caliber magnums.

Remember that a bent barrel boresight involves the bore axis at the muzzle. A bent barrel is best bore sighted with a collimator that eliminates all but the front 2 inches of the barrel.
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Agree. This barrel is bent. Saw it with naked eye when had it in lathe threading for brake. It was a split the difference game threading for brake.
 
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