If a manufacturer says their scope has 50 minutes of elevation adjustment can one assume that constitutes 50 minutes of drop from a typical zero? Or is the reticle always roughly centered when zeroed, in which case without an elevated base the example scope practically will only give about 25 minutes of drop?
Rifle Scopes Elevation range spec: Where does it start?
- Thread starter dbooksta
- Start date
Re: Elevation range spec: Where does it start?
Unless explicitly stated otherwise, you may assume that the quoted elevation adjustment is with the reticle centered, so that on a flat base, half of the quoted travel will be available to compensate for bullet drop.
It's actually a bit less than half, because somewhere around 4 to 4.5 MOA is used up in achieving a 100 yard or meter zero.
Unless explicitly stated otherwise, you may assume that the quoted elevation adjustment is with the reticle centered, so that on a flat base, half of the quoted travel will be available to compensate for bullet drop.
It's actually a bit less than half, because somewhere around 4 to 4.5 MOA is used up in achieving a 100 yard or meter zero.
Re: Elevation range spec: Where does it start?
Thanks. So in that case (and assuming nobody's shooting upside down) shouldn't we always buy or shim our sight bases to add at least a third of the quoted elevation range, so that we're zeroed near the top of the elevation adjustment?
Thanks. So in that case (and assuming nobody's shooting upside down) shouldn't we always buy or shim our sight bases to add at least a third of the quoted elevation range, so that we're zeroed near the top of the elevation adjustment?
Re: Elevation range spec: Where does it start?
Shims are not a good idea, unless you're going to bed the base with them.
What is better is a scope base with some elevation built in.
Common on precision rifles are bases with 20 MOA of slant. On a scope with 50 MOA of total adjustment on a flat base, you'll have only about 20 MOA of travel left for drop compensation after zeroing. With a 20 MOA base, you'd have 40 MOA left, which is adequate, although marginally, to get a .308 to 1000 yards.
If I had a scope with only 50 MOA of total adjustment, I'd probably want a 30 MOA base, if I could get one.
Shims are not a good idea, unless you're going to bed the base with them.
What is better is a scope base with some elevation built in.
Common on precision rifles are bases with 20 MOA of slant. On a scope with 50 MOA of total adjustment on a flat base, you'll have only about 20 MOA of travel left for drop compensation after zeroing. With a 20 MOA base, you'd have 40 MOA left, which is adequate, although marginally, to get a .308 to 1000 yards.
If I had a scope with only 50 MOA of total adjustment, I'd probably want a 30 MOA base, if I could get one.
Re: Elevation range spec: Where does it start?
It has to, if the mid-point of the adjustment range has the reticle centered.
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.
Which is probably more than anyone really wanted to know. But that's the amount of elevation which is consumed by a short range zero, which the interested readers, if there are any, can compute for their own setup.
And that's the amount by which scope with a centered reticle must use up some "up" elevation to get a zero.
It has to, if the mid-point of the adjustment range has the reticle centered.
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.
Which is probably more than anyone really wanted to know. But that's the amount of elevation which is consumed by a short range zero, which the interested readers, if there are any, can compute for their own setup.
And that's the amount by which scope with a centered reticle must use up some "up" elevation to get a zero.
Re: Elevation range spec: Where does it start?
I feel like I'm in math class again. Lindy, your on fire tonight.
I feel like I'm in math class again. Lindy, your on fire tonight.
Re: Elevation range spec: Where does it start?
As with most things, this subject has come up before, and most of that post was simply pasted in from a file.
If I actually had written each one of the posts I've made on this site, I'd probably have died from terminal carpal tunnel syndrome.
As with most things, this subject has come up before, and most of that post was simply pasted in from a file.
If I actually had written each one of the posts I've made on this site, I'd probably have died from terminal carpal tunnel syndrome.
Re: Elevation range spec: Where does it start?
I thought THAT syndrome came from doing something else to often!?
I thought THAT syndrome came from doing something else to often!?
Re: Elevation range spec: Where does it start?
Yeah, but your dick falls off before it gets terminal.
Yeah, but your dick falls off before it gets terminal.
Re: Elevation range spec: Where does it start?
Are you speaking from experience?
Are you speaking from experience?
Re: Elevation range spec: Where does it start?
Not yet...
Not yet...
