0 or 20moa base?

[Koda]

Punch the different values into your ballistic calculator for height over bore, note the impact to your drop table. You will find it doesn't have a significant impact to your firing solution out to 1000 yards. All this to say, your ballistic calculator will help with answering different questions by inputting alternative values so you can see the impact on your firing solution. Now it is worth doing things right since the more accurate your inputs the better data that is output. I only point this out so you have a realistic view of what inputs have minimal vs. significant impacts to your firing solution.

This is the method I commonly utilize (taken from another sight as it is written better than I would do):

Below is a formula to help you be a little more precise when determining sight height.

1.) Measure the bolt diameter and divide it in half.

2.) Measure the scope tube diameter and divide it in half. 1.000" / 2 = 0.500" (for 30mm tubes use 1.181")

3.) Measure the distance from the top of the bolt in the rifle to the bottom of the scope on the rifle.

4.) Add the numbers found in the steps 1-3.

Example: Remington 700 .308 with a Leupold Mark 4 M1 Extended Range Tactical Riflescope, 6.5x20x50mm

1) Bolt diameter .696". .696"/2= .348"

2) Scope tube diameter 30mm 1.181/2= .591"

3) Distance from top of bolt to bottom of scope = .75"

Sight Height = .348" + .591" + .75" = 1.68"

this is the method I use, but as I measured several points along the exposed top of the bolt I could "see" the 20MOA taking effect and think now I just over reacted. The difference at each end is .015". lol

I think I should just split that in the middle. Seems like the best point to measure would be under the turrets but they protrude too far to get my calipers in that spot.

 

[ORhutner]

this is the method I use, but as I measured several points along the exposed top of the bolt I could "see" the 20MOA taking effect and think now I just over reacted. The difference at each end is .015". lol

I think I should just split that in the middle. Seems like the best point to measure would be under the turrets but they protrude too far to get my calipers in that spot.

Yeah, input the extremes at both ends into your ballistic calculator and see the difference at 1000 yards for your shooting solution. My guess is that it is less than the human error that will occur. I agree though about it likely being best to split the difference.

 

[kopcicle]

When mathematics borders on semantics.
If you install a scope at 2.5" above bore. This does skew the results some.
I have a battle rattle in .308 that is just so.
What happens is that at a particular 5" MPBR zero the projectile will track at or near 2.5" above line of sight relatively longer than a projectile fired from a rifle with an optic mounted 1.5" above line of sight.
This is what happens when you mix angles with radii.

The result is that the MRT height is more or less maintained for several more yards and the MPBR is extended just a few feet/yards further.

If you really want to play with this it almost better to use a soft statistical method. Set an arbitrary distance above 2.5" like .100" and .100" below 2.5" and measure the distance where the projectile travels in that window. Now do that for 1.5" and 2.5" scope mounting. Now do the same for .200" above and below MRT.

Is it minutia or relevant? It's just numbers and well within shooter variables. In the end it's just interesting.
.

 

[YippeeKiYoRed]

To the OP's questions: I compete in High Power Long Range (800-1000 yards) so I'm very familiar with this.

If the max drop at 1000 yards is 27 MOA then, theoretically, you should be fine with a total adjustable range of 75 MOA.

1. If you have not already done so, run a ballistics engine calculation to confirm the expected drop. Use a 100 yard zero.
2. Now sight-in the rifle at 100 yards.
3. Either write down where the elevation turret is at or take a photo.
4. Try adding the required elevation for 1000 yards and verify you don't run out of turret.
5. Adjust the turret back to the 100 yard setting.
6. Verify you're back at zero with one or two shots.

With a quality scope like a Leupold there won't be any adverse effects shooting at 100 yards with a 20 MOA base, if you decide to go that way.

 

[Koda]

If the max drop at 1000 yards is 27 MOA then, theoretically, you should be fine with a total adjustable range of 75 MOA.

What originally happened is I was doing my math wrong converting inches to MOA. I thought I was running out of turret so I decided to buy the MOA base and remount the scope. The math kept bothering me why I would run out of turret with a nice Leupold with 75moa of travel so I kept working the math until it dawned on my.
Math isnt my strong point, but once I "saw" it was obvious.... I was forgetting to muliply 1/4moa click by the distance. I also learned I have no need to convert to inches when moa is written right there on the dial.
anyways, I figured it out after I bought and mounted the 20moa base so now Im mentally deciding if I want to go back and sell or return my new base or just keep them. Since Im hear Im leaning towards keeping them as I dont see any disadvantage over the "optical center".

 

[ORhutner]

What originally happened is I was doing my math wrong converting inches to MOA. I thought I was running out of turret so I decided to buy the MOA base and remount the scope. The math kept bothering me why I would run out of turret with a nice Leupold with 75moa of travel so I kept working the math until it dawned on my.
Math isnt my strong point, but once I "saw" it was obvious.... I was forgetting to muliply 1/4moa click by the distance. I also learned I have no need to convert to inches when moa is written right there on the dial.
anyways, I figured it out after I bought and mounted the 20moa base so now Im mentally deciding if I want to go back and sell or return my new base or just keep them. Since Im hear Im leaning towards keeping them as I dont see any disadvantage over the "optical center".

Keep it as is, your not hurting anything with a quality optic like your VX6. How much money are you going to burn in ammo re-zeroing after swapping bases? I see the 20 MOA base as an advantage when you get the opportunity to extend your range out past 1,000 yards.