0 or 20moa base?

[Koda]

If my scope has 75moa of elevation travel, do I need a 20moa base to shoot out to 1000yds?

I realize this is caliber specific so this is a 1000yd capable rifle and caliber, 280AI with a Leupold VX-6HD 3x18x44.

Second question: is there any harm in zeroing with a 20moa base at 100yds? ( Ive heard somewhere its better to have your zero as close to the scope axis as possible. )

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[solv3nt]

Is that total travel? I'm too lazy to calc, but more than likely.

 

[Koda]

Is that total travel? I'm too lazy to calc, but more than likely.

its not entirely clear but thats the way I interpret it on their product webpage. 75moa total travel is 37.5moa one direction from zero. (That said mine stopped at 31....)

 

[ORhutner]

I am not familiar with the 280ai's ballistics but assuming it is similar to something like a 6.5 creed your looking at 30 - 32 MOA to get to 1000 yards, this is just an estimate though off my own known data. If everything is perfect with your mount, action and rings and the scope is zeroed for point of aim/impact at 100 yards at the middle of the adjustment range or lower, you would have enough elevation to get to 1,000 yards. If it were me, I would use a 20 MOA rail as that is a lot of variables that you need to line up.

I have been told that your scope is best optically when in the middle of the adjustment range but have not done any independent research or have any first hand experience that backs up that statement. I personally do not notice any changes to optical quality with my Leupold, Nightforce, Swaro or ZCO optics when dialed.

 

[ORhutner]

its not entirely clear but thats the way I interpret it on their product webpage. 75moa total travel is 37.5moa one direction from zero. (That said mine stopped at 31....)
View attachment 1450598

That is 75 MOA of total vertical adjustment range. So if optical center aligns with mechanical center you would have 37.5 MOA of up or down adjustment from center.

 

[Flopsweat]

So it sounds like you'd still be able to zero at 100 yards with a 20 MOA base.

 

[Koda]

I am not familiar with the 280ai's ballistics but assuming it is similar to something like a 6.5 creed your looking at 30 - 32 MOA to get to 1000 yards, this is just an estimate though off my own known data. If everything is perfect with your mount, action and rings and the scope is zeroed for point of aim/impact at 100 yards at the middle of the adjustment range or lower, you would have enough elevation to get to 1,000 yards. If it were me, I would use a 20 MOA rail as that is a lot of variables that you need to line up.

I have been told that your scope is best optically when in the middle of the adjustment range but have not done any independent research or have any first hand experience that backs up that statement. I personally do not notice any changes to optical quality with my Leupold, Nightforce, Swaro or ZCO optics when dialed.

280AI ballistics is comparable to 7mm Remington Magnum ballistics. For the handload I have for this Im estimating about 24 to 27moa to get out to 1000 yds.

I just assumed I would need a 20moa base to shoot past say 500yds so I installed one but now Im thinking I may have over reacted.... hence my second question. Ive also heard its "best" to be zeroed as close to optical center as possible, but im not certain it matters with todays scope technology?

 

[Member 53328]

I try to stick with 0 MOA base and see if I bottom out at further distances. If I have to bump up to a 20 MOA I will or I'll just purchase a mount that has the desired MOA built in.

 

[kopcicle]

ts "best" to be zeroed as close to optical center as possible,

This allows for the maximum amount of windage to cranked in as opposed to severely limiting windage adjustment at extreme elevation.

If you're going to be shooting 1.000 yards, what is the point of a 100 yard zero?
For a rifle that will see sporting (hunting) use as well as long range paper punching how come a 5" MPBR zero isn't a good idea?

Now if you're really good at measurements and have a ballistic solver that understands the 20 MOA rail (or not, it's just math) I think you'll find that your near field zero could be inside of 15 yards on the way to 1,000 yard impact!

Find a load in a node that is repeatable then zero for no more than 2.5" over or under line of sight and call it done.
This way you can return to zero and be sure of hitting any 5" circle from muzzle to 280 ish yards with a dead hold.

Your mileage, maths, ballistics, and trigger finger may vary but the basics are the basics.

 

[Koda]

This allows for the maximum amount of windage to cranked in as opposed to severely limiting windage adjustment at extreme elevation.

If you're going to be shooting 1.000 yards, what is the point of a 100 yard zero?
For a rifle that will see sporting (hunting) use as well as long range paper punching how come a 5" MPBR zero isn't a good idea?

Now if you're really good at measurements and have a ballistic solver that understands the 20 MOA rail (or not, it's just math) I think you'll find that your near field zero could be inside of 15 yards on the way to 1,000 yard impact!

Find a load in a node that is repeatable then zero for no more than 2.5" over or under line of sight and call it done.
This way you can return to zero and be sure of hitting any 5" circle from muzzle to 280 ish yards with a dead hold.

Your mileage, maths, ballistics, and trigger finger may vary but the basics are the basics.

So the farther from optical center the less windage adjustment is available? This kinda makes sense to me if I understand trying to align two tubes by pushing one from its sides.

Primarily, this is a hunting rifle. I will not be hunting out to 1000 yds but the rifle and caliber is capable so I wanted to also explore long range shooting, not that I will do a lot of it but this is the first rifle Ive owned capable of it.


I dont want to do a MPBR zero with this scope since it has a zero stop and most hunting ranges are under 100yds. I can also dial to 200yds if I want to hunt variable distance terrain and use the MPBR option.

 

[Koda]

This allows for the maximum amount of windage to cranked in as opposed to severely limiting windage adjustment at extreme elevation.

thinking more on this, if using a 0moa base and shooting long range then the elevation turret would be more maxed out to its limits restricting any potential windage needs?
In short: would a 20moa base yield more windage adjustment at any distance?

 

[Member 53328]

thinking more on this, if using a 0moa base and shooting long range then the elevation turret would be more maxed out to its limits restricting any potential windage needs?
In short: would a 20moa base yield more windage adjustment at any distance?

It would yield more elevation. Not sure it would benefit you in windage. But I may be wrong.

 

[solv3nt]

Yeah, I'm not sure how you're getting horizontal adjustment out of a vertical element.

 

[Koda]

It would yield more elevation. Not sure it would benefit you in windage. But I may be wrong.

because your using less elevation from optical center to adjust windage from....

 

[P7M13]

Unless you plan on shooting a lot at 1K and farther, I'd say no to a 20 MOA base.
I would also select a reticle that gave me mils rather than fine/thick crosshairs only.
JMO.
I have two rifles with 20 MOA rails, and both are equipped with older Leupolds that have <50 MOA total travel. Most of my shooting on both of those has been 500 yards

 

[kopcicle]

Maybe, just maybe you're not getting the complete dope.
For 154gr and 3000 fps
near field zero is about 27 yards
MRT is 135 yards, or 2.5" above line of sight
MPBR is 280 yards.
MPBR zero is 237 yards

So, anything inside of 100 hold low but no more that 2"
Anything over 200 hold over but no more than 2"
Both the above are only if you desire the additional precision. Accuracy is all on you.

Maybe it's just me but unless I'm up against a near steady 20mph full value hold I won't crank it in.
And unless I'm more than 10 degrees off level I won't crank it in.

For brush guns in western Washington I do much the same but with a 3" MPBR.

I have rarely had the time or inclination to put anything in the scope when hunting. I hold off MPBR.
The only exception to date has been Antelope at over 400 yards.

Just for fun

Near field zero for the same 154gr at 3,000 fps for 1000 yards is maybe 7 yards!
Do keep in mind that this is center of reticle above line of sight and requires careful measurement because an error in zero at such close range can result in feet if not yards of elevation at 1,000 yards.
MRT is 98.61 inches at 560 yards
Still super sonic at 1480 FPS and about 750 f/lbs at 1000

If nothing else it was fun to look at the maths. Even if you choose otherwise it proved interesting.

 

[Koda]

Yeah, I'm not sure how you're getting horizontal adjustment out of a vertical element.

when you start with two tubes that are perfectly centered (concentric) and tilt one in one direction you get less range of motion in the other direction due to the stationary tube being round.

 

[kopcicle]

I would also select a reticle that gave me mils rather than fine/thick crosshairs only.

We went to the same school separately

 

[Member 53328]

because your using less elevation from optical center to adjust windage from....

Windage left and right. With the 20 MOA base adds a slant to you scope allowing more elevation. Not sure how the slant up and down would give you more adjustment left and right. But I'm no sniper and am just getting into distances past 500 yards. So I'm also learning and love learning new things. I may be too simple minded. Haha.

I also prefer mils as that's what I'm familiar with from the military. Easier to count for me personally.

 

[kopcicle]

@P7M13
Of course all the above maths go out the window when I'm using the fine target dot and the 32x.
Then all the dope goes in the scope.