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Old February 26, 2020, 07:10 PM   #1
kilotanker22
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Never had this problem before.

So picture this. New rifle setup. Savage 110 tactical with 20 MOA EGW rail. Vortex Viper PST. Vortex Pro Rings. Everything leveled, mounted and torqued correctly. (Pretty sure)

Just to get zeroed at 100 yards I am almost topped out on elevation..... I should be having the opposite problem. Scope has 65 MOA of adjustment. I am already most of the way through the fourth revolution up... I have 15 moa of UP adjustment left. Without that 20 MOA base I would not even be able to zero.

Gonna pull it apart and measure each of the rings as well as the base. Double check ring placement.

Any ideas? Before I buy some other type of mount, I would like to get to the bottom of the cause of this problem.

And yes the base is installed correctly
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Old February 26, 2020, 07:36 PM   #2
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I understand you said the base is installed correctly. It might very well be..

But if you put on a 20 MOA base and are nearly out of elevation my first thought was the base is reversed.

I suppose the machinist producing the bases could have loaded one backwards.

You might measure. The thin end of the base should be toward the muzzle.
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Old February 26, 2020, 07:49 PM   #3
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I've looked through them but never had one--one thing that comes to mind is that your total elevation may not all be available as "up"--sometimes part of the the turret's total range is devoted to "dial down" which may be needed for closer range shots. Just a guess. ; )
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Old February 26, 2020, 09:26 PM   #4
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Shiot it at 400 see where it hits.
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Old February 26, 2020, 10:08 PM   #5
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Not sure it matters much where it is at 400. I don't have even remotely enough elevation left to shoot to even 1000. Dead on at 100 yards only leaves me 15 MOA to come up.
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Old February 26, 2020, 10:09 PM   #6
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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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Old February 26, 2020, 10:13 PM   #7
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Hey kilo...

I just put my 110 TAC together the other day...before I put the rings on for adjustment I checked rail screws...only 1 was even snug...the other 3 were not even close,,,,its a wonder the front 2 didn't fall out in transport...sure glad I checked them

My scope has 80 min of adjustment so I took it to the bottom and dial up 20 min...it was right there.....3 min left and I'm good for load work up....it was cold today but I couldn't wait any longer...lol..
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Old February 26, 2020, 10:14 PM   #8
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Quote:
Originally Posted by stagpanther View Post
I've looked through them but never had one--one thing that comes to mind is that your total elevation may not all be available as "up"--sometimes part of the the turret's total range is devoted to "dial down" which may be needed for closer range shots. Just a guess. ; )
Dedicated to dial down??? That makes no sense to me. A vertical adjustment range is a vertical adjustment range. I couldn't imagine a scope company making a portion of the vertical adjustment unavailable and dedicated to dial down.. they would also need a separate dial to do so. And even if that was the case. I should have to dial down to account for the 20 MOA base.
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Old February 26, 2020, 10:15 PM   #9
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Originally Posted by ocharry View Post
Hey kilo...

I just put my 110 TAC together the other day...before I put the rings on for adjustment I checked rail screws...only 1 was even snug...the other 3 were not even close,,,,its a wonder the front 2 didn't fall out in transport...sure glad I checked them

My scope has 80 min of adjustment so I took it to the bottom and dial up 20 min...it was right there.....3 min left and I'm good for load work up
I mounted the base myself and made sure they were torqued and loctited
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Old February 26, 2020, 10:27 PM   #10
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Quote:
Dedicated to dial down??? That makes no sense to me. A vertical adjustment range is a vertical adjustment range. I couldn't imagine a scope company making a portion of the vertical adjustment unavailable and dedicated to dial down.. they would also need a separate dial to do so. And even if that was the case. I should have to dial down to account for the 20 MOA base.
Sorry--disregard my foolish comment--I was referring to my 5HD which has a "reserve" beyond zero stop. I don't know your scope.
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Old February 26, 2020, 10:32 PM   #11
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The last time I saw something like that that was not sights/optics/rings/bases related, the barrel had a crooked crown and muzzle face.
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Old February 26, 2020, 10:38 PM   #12
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So if you have 65 min...that's 32.5 up and gown from mechanical zero..

If I'm thinking right you should have about 12.5 min left to get to the bottom of adjustment

I agree ..the numbers dont add up

But if the base was on backwards.....just saying...then you should only have that 12.5 min left at the top

No offense.... But I would be taking it apart and checking things out...again

Are the rings the same ??? Saddle to bottom of radius??

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Old February 27, 2020, 12:57 AM   #13
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Quote:
Originally Posted by stagpanther View Post
If you zero-stop your turret for a particular cartridge at a particular distance, then I can see leaving "dial-down" available on the turrets ring. I'm not using the right language perhaps--in other words don't use all of the entire turret's revolutions to zero-stop.
That makes sense. I intend to use the zero stop once zeroed, but that couldn't cause my problem here.

I may have found the issue. When I mounted the scope, I must have inadvertently slid the scope back on the rifle. I normally mount my front ring edge about an eighth of an inch from where the tube begins to transition into the Objective. I noticed thee edge of the front ring was right on that datum line. I can not be 100% certain that the edge of the ring being on that datum line did not can't the scope up slightly at the front. It couldn't have been more than a couple thousandths of an inch I don't think. I don't think that it would cause a 60 minute of angle or so change. A change that large would be easily seen by someone looking for it.
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Old February 27, 2020, 01:46 AM   #14
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I'm sorry, I was probably talking off the top of my head since I'm not familiar with that scope. I think some higher power scopes do have issues when zeroing for a particular cartridge at say a closer range when using a canted base. Possibly a longer zero distance will enable you to "regain" some of that elevation.

Quote:
I can not be 100% certain that the edge of the ring being on that datum line did not can't the scope up slightly at the front. It couldn't have been more than a couple thousandths of an inch I don't think. I don't think that it would cause a 60 minute of angle or so change. A change that large would be easily seen by someone looking for it.
An asymmetry in scope alignment can cause the internals to get knocked out of whack, especially if it gets loaded by torque on the rings and recoil repetitively. I've done it on a couple cheaper scopes, these days I take the extra time to carefully true and lap rings to be as least stressful on the scope as possible. It's a rare rifle I've worked on that didn't have over-torqued rings that were also not perfectly mated to the scope body.
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Last edited by stagpanther; February 27, 2020 at 02:02 AM.
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Old February 27, 2020, 02:57 AM   #15
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I'm assuming flat rear receiver.

Take your scope rings off. Pull the screws out of the base. Press base with your fingers flat on the front receiver. Check for gap at rear of receiver.
Now reverse proceedure.

My wife's round receiver needed shimmed to set the base flat. I've got about 5 MOA left of adjustmet. Need a 10 MOA base.
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Old February 27, 2020, 01:25 PM   #16
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I was kind of curious so I pulled out my 338 lapua rig which has a sweet Leupold 7 x 35 5HD atop it--and low and behold I discovered that it too "loses" some of the dial up elevation from my zero-stop setting for 100 yds. It has a built in elevation range of 100 MOA--plus I have it mounted on a 20 MOA base. It's probably not unusual for a longer range scope to use some of that elevation simply because your scope is inclined to give you the extra elevation needed at longer ranges so you might end up using a lot of that dial-up for close zero settings. It may be pure coincidence, but on my scope that 1/2 revolution is roughly analogous to 25 MOA.
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Old February 27, 2020, 01:39 PM   #17
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OK, I took it all apart and measured everything today.

The rings are the same height (less than 5 ten thousands difference in height.
The base is in fact not a 20 MOA base. I removed the base and measured the thickness between the front and rear. All measurements were within .0015.

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?

When you want to move your point of impact up you move the reticle down. So moving the whole scope down should have a similar effect. Where my zero is now, If I add just the 20MOA base I will be right around the center of the adjustment range. If I can also use the low rings with the new Weaver rail then that should eat up a good porton of down adjustment and get me right about where I wanted to be (toward the bottom of the scopes available adjustment.
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Old February 27, 2020, 01:40 PM   #18
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Originally Posted by stagpanther View Post
I was kind of curious so I pulled out my 338 lapua rig which has a sweet Leupold 7 x 35 5HD atop it--and low and behold I discovered that it too "loses" some of the dial up elevation from my zero-stop setting for 100 yds. It has a built in elevation range of 100 MOA--plus I have it mounted on a 20 MOA base. It's probably not unusual for a longer range scope to use some of that elevation simply because your scope is inclined to give you the extra elevation needed at longer ranges so you might end up using a lot of that dial-up for close zero settings. It may be pure coincidence, but on my scope that 1/2 revolution is roughly analogous to 25 MOA.
Stag, It would be close to the same for this scope. Except my zero stop is not built in. Once I zero the scope to the rifle, I have to add the provided shims to prevent the turret from rotating below my zero point.
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Old February 27, 2020, 01:43 PM   #19
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Now hopefully the Weaver base I just bought is not much shorter than the EGW base. Otherwise I might not be able to use the low rings I just bought. As it is right now, I have .55" I can come down Before the objective contacts the barrel.
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Old February 27, 2020, 01:56 PM   #20
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Quote:
I have 15 moa of UP adjustment left. Without that 20 MOA base I would not even be able to zero.
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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Old February 27, 2020, 01:56 PM   #21
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Quote:
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?
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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Last edited by stagpanther; February 27, 2020 at 02:48 PM.
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Old February 27, 2020, 02:45 PM   #22
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Originally Posted by kilotanker22 View Post
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.
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.
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Old February 27, 2020, 02:59 PM   #23
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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.
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Old February 27, 2020, 03:06 PM   #24
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Originally Posted by 44 AMP View Post
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....
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.
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Old February 27, 2020, 03:07 PM   #25
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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.
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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