I have a Leupold Mark 4 6.5-20x50mm LR/T M1 mounted on a Nightforce 40 MOA Base on my Remington 338LM. I believe the scope has 70 MOA of internal adjustment. Will I be able to zero the rifle at 100 yards? If not, what is the minimum distance I can zero the rifle to? Thanks in advance.
Rifle Scopes Enough Elevation To Zero At 100 yards
- Thread starter Bamafan
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Re: Enough Elevation To Zero At 100 yards
Assuming that you're correct, and the scope has 70 MOA of adjustment, that's 35 up and 35 down with the reticle in the middle of the tube.
Add in a 40 MOA base, and now you've got 75 MOA up, and -5 MOA down.
Since you need about 4.25 MOA of elevation for a 100 yard zero, depending on your load and the scope height above the bore, you're going to be right on the edge of being able to get a 100 yard zero. And if your base holes are not perfectly aligned with the bore, you may not have enough windage adjustment as the scope bottoms out to get a windage zero at your elevation zero.
But scope specifications are always a little off. If you already have the base and the scope, you might as well try it, and see if it works.
Assuming that you're correct, and the scope has 70 MOA of adjustment, that's 35 up and 35 down with the reticle in the middle of the tube.
Add in a 40 MOA base, and now you've got 75 MOA up, and -5 MOA down.
Since you need about 4.25 MOA of elevation for a 100 yard zero, depending on your load and the scope height above the bore, you're going to be right on the edge of being able to get a 100 yard zero. And if your base holes are not perfectly aligned with the bore, you may not have enough windage adjustment as the scope bottoms out to get a windage zero at your elevation zero.
But scope specifications are always a little off. If you already have the base and the scope, you might as well try it, and see if it works.
Re: Enough Elevation To Zero At 100 yards
You would have either the mil-dot or tactical milling reticle in your Mark 4.
Worst case scenario and you dont make a 100 yard zero, just work out the hash mark on the reticle that corresponds with a 100 yard hit.
You would have either the mil-dot or tactical milling reticle in your Mark 4.
Worst case scenario and you dont make a 100 yard zero, just work out the hash mark on the reticle that corresponds with a 100 yard hit.
Re: Enough Elevation To Zero At 100 yards
Lindy,
How do you figure he needs 4.5MOA for a 100 yd zero? Is this DN moa? I'm not arguing with you, I just don't understand that.
If he doesn't have enough MOA, a gunsmith with should be able to mill the base down a bit and give him a little more.
Lindy,
How do you figure he needs 4.5MOA for a 100 yd zero? Is this DN moa? I'm not arguing with you, I just don't understand that.
If he doesn't have enough MOA, a gunsmith with should be able to mill the base down a bit and give him a little more.
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">Assuming that you're correct, and the scope has 70 MOA of adjustment, that's 35 up and 35 down with the reticle in the middle of the tube.
Add in a 40 MOA base, and now you've got 75 MOA up, and -5 MOA down.
Since you need about 4.25 MOA of elevation for a 100 yard zero, depending on your load and the scope height above the bore, you're going to be right on the edge of being able to get a 100 yard zero. And if your base holes are not perfectly aligned with the bore, you may not have enough windage adjustment as the scope bottoms out to get a windage zero at your elevation zero.
But scope specifications are always a little off. If you already have the base and the scope, you might as well try it, and see if it works.
</div></div>
Maybe you mis-typed (or maybe I'm an idiot) but if the scope has 70 moa of <span style="font-style: italic">mechanical </span>travel, how does a 40 moa base add 5 moa travel to the equation. Doesn't it just shift the scale?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">Assuming that you're correct, and the scope has 70 MOA of adjustment, that's 35 up and 35 down with the reticle in the middle of the tube.
Add in a 40 MOA base, and now you've got 75 MOA up, and -5 MOA down.
Since you need about 4.25 MOA of elevation for a 100 yard zero, depending on your load and the scope height above the bore, you're going to be right on the edge of being able to get a 100 yard zero. And if your base holes are not perfectly aligned with the bore, you may not have enough windage adjustment as the scope bottoms out to get a windage zero at your elevation zero.
But scope specifications are always a little off. If you already have the base and the scope, you might as well try it, and see if it works.
</div></div>
Maybe you mis-typed (or maybe I'm an idiot) but if the scope has 70 moa of <span style="font-style: italic">mechanical </span>travel, how does a 40 moa base add 5 moa travel to the equation. Doesn't it just shift the scale?
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Maybe you mis-typed (or maybe I'm an idiot) but if the scope has 70 moa of mechanical travel, how does a 40 moa base add 5 moa travel to the equation.</div></div>
If you add (75) and (-5), you get 70.
The (-5 MOA) refers to the fact that with that base, the scope now cannot dial down (actually, up) to where the line of sight is parallel with the bore.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">How do you figure he needs 4.5MOA for a 100 yd zero? Is this DN moa? I'm not arguing with you, I just don't understand that.</div></div>
There are two angular components to a short-range - say, 100 yard - zero.
One is compensation for the height of the scope over the bore. That angle may be computed as:
angle = arctan (height above bore / distance to target)
In the case of my AI, for example, with a height above bore of 1.75 inches, at 100 yards (3600 inches) it's:
angle = arctan(1.75 / 3600) = .03 degrees or 1.67 MOA
The other component is the drop from the muzzle to the zero range. With my load at 100 yards, that's about 2.7 inches, or, using the same formula above, about 2.58 MOA.
Add those two up, and it's about 4.25 MOA or about 1.25 mil.
So, if, with his base, he winds up about 5 MOA below having the line of sight parallel with the bore - that's the -5 MOA I calculated - he's going to be <span style="font-style: italic">close</span> to a hundred yard zero.
But, as I said, probably too close. A 30 MOA base would be a better choice for a .338 LM which is used for extra-long-range.
With a .308, you'd never need more than 20 MOA.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Maybe you mis-typed (or maybe I'm an idiot) but if the scope has 70 moa of mechanical travel, how does a 40 moa base add 5 moa travel to the equation.</div></div>
If you add (75) and (-5), you get 70.
The (-5 MOA) refers to the fact that with that base, the scope now cannot dial down (actually, up) to where the line of sight is parallel with the bore.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">How do you figure he needs 4.5MOA for a 100 yd zero? Is this DN moa? I'm not arguing with you, I just don't understand that.</div></div>
There are two angular components to a short-range - say, 100 yard - zero.
One is compensation for the height of the scope over the bore. That angle may be computed as:
angle = arctan (height above bore / distance to target)
In the case of my AI, for example, with a height above bore of 1.75 inches, at 100 yards (3600 inches) it's:
angle = arctan(1.75 / 3600) = .03 degrees or 1.67 MOA
The other component is the drop from the muzzle to the zero range. With my load at 100 yards, that's about 2.7 inches, or, using the same formula above, about 2.58 MOA.
Add those two up, and it's about 4.25 MOA or about 1.25 mil.
So, if, with his base, he winds up about 5 MOA below having the line of sight parallel with the bore - that's the -5 MOA I calculated - he's going to be <span style="font-style: italic">close</span> to a hundred yard zero.
But, as I said, probably too close. A 30 MOA base would be a better choice for a .338 LM which is used for extra-long-range.
With a .308, you'd never need more than 20 MOA.
Re: Enough Elevation To Zero At 100 yards
Lindy, thank you for the advice. One more question. With 70 MOA adjustment in windage as well, am I okay in that regard or do I need to get a 30 MOA base.
Lindy, thank you for the advice. One more question. With 70 MOA adjustment in windage as well, am I okay in that regard or do I need to get a 30 MOA base.
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">If you add (75) and (-5), you get 70.
The (-5 MOA) refers to the fact that with that base, the scope now cannot dial down (actually, up) to where the line of sight is parallel with the bore.
</div></div>
Oh I gotcha...you weren't referring to turret travel above and below zero. I'm whole again. Thanks.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">If you add (75) and (-5), you get 70.
The (-5 MOA) refers to the fact that with that base, the scope now cannot dial down (actually, up) to where the line of sight is parallel with the bore.
</div></div>
Oh I gotcha...you weren't referring to turret travel above and below zero. I'm whole again. Thanks.
Re: Enough Elevation To Zero At 100 yards
I'd get the 30 MOA base. With it, after a 100 yard zero, you'll still have about 60 MOA of elevation to dial up, which will give enough elevation to shoot a .338 LM to as far as the bullet will stay supersonic on an ICAO-standard day.
If you want to shoot much beyond about 1600 yards, depending on conditions, you'll need to hold over using the reticle with that scope. If you are serious about shooting beyond that distance, you might wish to consider a scope with more elevation adjustment.
Scopes commonly used in ELR shooting will have 100 MOA or more of internal adjustment.
I'd get the 30 MOA base. With it, after a 100 yard zero, you'll still have about 60 MOA of elevation to dial up, which will give enough elevation to shoot a .338 LM to as far as the bullet will stay supersonic on an ICAO-standard day.
If you want to shoot much beyond about 1600 yards, depending on conditions, you'll need to hold over using the reticle with that scope. If you are serious about shooting beyond that distance, you might wish to consider a scope with more elevation adjustment.
Scopes commonly used in ELR shooting will have 100 MOA or more of internal adjustment.
Re: Enough Elevation To Zero At 100 yards
Lindy,
While we're on the topic, I'm having a bit of a dilemma. I have a second USO on the way for a 98B. Thinking I might want to go with a 25X over the 17X SN3 I already have, the USO rep talked me into going with a 34mm tube for additional elevation travel.
The problem is that mounting options that are acceptable to me are limited in 34mm. My question is...shouldn't a .338LM be able to reach 1500+ yards with a SN3 TPAL with a 30mm tube on a 20moa base considering that it does have EREK? And secondly, generally how much additional elevation is the extra 4mm tube diameter typically worth?
Lindy,
While we're on the topic, I'm having a bit of a dilemma. I have a second USO on the way for a 98B. Thinking I might want to go with a 25X over the 17X SN3 I already have, the USO rep talked me into going with a 34mm tube for additional elevation travel.
The problem is that mounting options that are acceptable to me are limited in 34mm. My question is...shouldn't a .338LM be able to reach 1500+ yards with a SN3 TPAL with a 30mm tube on a 20moa base considering that it does have EREK? And secondly, generally how much additional elevation is the extra 4mm tube diameter typically worth?
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">shouldn't a .338LM be able to reach 1500+ yards with a SN3 TPAL with a 30mm tube on a 20moa base considering that it does have EREK?</div></div> I'm pretty sure that it would. Add half the total travel to the 20 MOA, and calculate whether that would get you to the distance you want to shoot.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">And secondly, generally how much additional elevation is the extra 4mm tube diameter typically worth?</div></div>
Can't answer that. Ask the guys at USO, or look at the scope specs.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">shouldn't a .338LM be able to reach 1500+ yards with a SN3 TPAL with a 30mm tube on a 20moa base considering that it does have EREK?</div></div> I'm pretty sure that it would. Add half the total travel to the 20 MOA, and calculate whether that would get you to the distance you want to shoot.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">And secondly, generally how much additional elevation is the extra 4mm tube diameter typically worth?</div></div>
Can't answer that. Ask the guys at USO, or look at the scope specs.
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"> I'm pretty sure that it would. Add half the total travel to the 20 MOA, and calculate whether that would get you to the distance you want to shoot.
</div></div>
I'm not understanding "add half the total". With an EREK setup the erector is bottomed at my zero and there's only maybe 4/10's of a mil travel below zero. I have 22 mils of elevation above my 100 yrd zero...would I not add that to the 20moa of the base? (after converting to moa of course)
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"> I'm pretty sure that it would. Add half the total travel to the 20 MOA, and calculate whether that would get you to the distance you want to shoot.
</div></div>
I'm not understanding "add half the total". With an EREK setup the erector is bottomed at my zero and there's only maybe 4/10's of a mil travel below zero. I have 22 mils of elevation above my 100 yrd zero...would I not add that to the 20moa of the base? (after converting to moa of course)
Re: Enough Elevation To Zero At 100 yards
Its important to know the units you are actually working in. 22 Mils IS in fact approximately 75 MOA of travel.
22 Mils X 3.43 = MOA equivalent
Its important to know the units you are actually working in. 22 Mils IS in fact approximately 75 MOA of travel.
22 Mils X 3.43 = MOA equivalent
Re: Enough Elevation To Zero At 100 yards
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Its important to know the units you are actually working in. 22 Mils IS in fact approximately 75 MOA of travel.
22 Mils X 3.43 = MOA equivalent </div></div>That's how I arrived at it...thanks.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Its important to know the units you are actually working in. 22 Mils IS in fact approximately 75 MOA of travel.
22 Mils X 3.43 = MOA equivalent </div></div>That's how I arrived at it...thanks.
Re: Enough Elevation To Zero At 100 yards
So, if you have that much travel available, you probably don't need a 20 MOA base to get the .338 LM as far as you can practically shoot it. It would, though, get the reticle up a bit further in the tube, which is some scopes enhances optical clarity.
So, if you have that much travel available, you probably don't need a 20 MOA base to get the .338 LM as far as you can practically shoot it. It would, though, get the reticle up a bit further in the tube, which is some scopes enhances optical clarity.
Re: Enough Elevation To Zero At 100 yards
I should have clarified...this is what I get <span style="text-decoration: underline">with</span> a 20moa base. I was trying to fugure if it was really necessary to go with a 34mm main tube over the 30mm for the extra elevation it would afford but I don't think I need it. Thanks for the help guys.
I should have clarified...this is what I get <span style="text-decoration: underline">with</span> a 20moa base. I was trying to fugure if it was really necessary to go with a 34mm main tube over the 30mm for the extra elevation it would afford but I don't think I need it. Thanks for the help guys.
I would like to try and resurrect this thread because i have a similar, if not the same, question but for a different configuration.
I am building a 300PRC for some extreme long range shooting (1,000-2,000 yards). When not shooting at those distances, i want to be able to get a 100yd zero and shoot in some local F-Class matches at 300-800 yards. I do not yet have the rifle built but COMING SOON. I am estimating that my load will include a 230gr Berger Hybrid with a muzzle velocity of appx 2800fps.
My action is a Defiance Machine Rukus LA with a 20MOA picatinny rail
I am considering the following scopes for this new build:
Sooooo.... my dilemma is two fold.
In order to mount my scope high enough to get a 100yard zero at the mechanical bottom of the scope's elevation adjustment:
1. What would be the best height for my scope mount?
2. How is that calculated?
I acknowledge the formula provided in this thread but not sure how to apply it for MRAD instead of MOA.
Thanks in advance
I am building a 300PRC for some extreme long range shooting (1,000-2,000 yards). When not shooting at those distances, i want to be able to get a 100yd zero and shoot in some local F-Class matches at 300-800 yards. I do not yet have the rifle built but COMING SOON. I am estimating that my load will include a 230gr Berger Hybrid with a muzzle velocity of appx 2800fps.
My action is a Defiance Machine Rukus LA with a 20MOA picatinny rail
I am considering the following scopes for this new build:
- Zeiss LRP S3 6-36x56 with a total of 32MRAD elevation
- Nightforce ATACR 7-35x56 with a total of 29MRAD elevation
- Vortex Razor HD Gen III 6-36x56 with a total of 36MRAD elevation
Sooooo.... my dilemma is two fold.
In order to mount my scope high enough to get a 100yard zero at the mechanical bottom of the scope's elevation adjustment:
1. What would be the best height for my scope mount?
2. How is that calculated?
I acknowledge the formula provided in this thread but not sure how to apply it for MRAD instead of MOA.
Thanks in advance
If you do not understand how to apply the math to MRAD, simply convert all the MRAD figures to MOA and math away.
Are there any scopes on the market that have over 100 MOA/30 Mill internal elevation adjustment for under $2000 dollars?
I know the Tract Toric 4.5-30x56 has 100 MOA/30 Mil internal elevation adjustment and it goes for around $1400 to $1600.
Would a rifle chambered in 300 PRC using the Tract Toric 4.5-30x56 scope that has 100 MOA/30 Mil of internal elevation adjustment be able to maintain a zero at 100 yards with a 40 MOA base/rail?
I know the Tract Toric 4.5-30x56 has 100 MOA/30 Mil internal elevation adjustment and it goes for around $1400 to $1600.
Would a rifle chambered in 300 PRC using the Tract Toric 4.5-30x56 scope that has 100 MOA/30 Mil of internal elevation adjustment be able to maintain a zero at 100 yards with a 40 MOA base/rail?
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