Minimum Long Range Scope Adjustment

[257Roberts]

Question: What do you folks feel the MINIMUM amount of elevation scope adjustment is needed for say 1000 yards with a 20MOA angled base? All my current inventory are 60MOA+ total adjustment.

All the scopes I currently have include more than enough adjustment with a 20MOA base.

I am looking at a very rugged highly regarded fixed 25 power benchrest scope, but it only has 40MOA total adjustment.
I have a 20MOA base on all my long range rifles, but I'm concerned that ±20MOA still wont be enough? Or maybe close to maxing out?

If my math is right, even a 223 only needs about 35-40MOA for 1000 yards, and in theory knocking 20MOA off that with a base should make ±20MOA range marginally feasible. So many of the true long range cartridges require less than 30MOA total, so I think this range still works.

Id hate to buy it only to be disappointed.

Thoughts?

 

[Clark]

I build and scope about 3 rifles per year.
I have shot over 50 deer and antelope at a median range of 400 yards.
I zero at 200 yards and never shoot with more than 8moa correction.
More than 8 moa I have done a couple times, but they were hail Mary shots.

 

[NZ_Fclass]

Well, You would have no problem getting a 308 with 155g out to 1000. It's an interesting sublect, explained to me by a scope retailer, years ago. Some of the earlyUS and many European scopes 30mm tubes had no more elevation/windage than 1 in tubes. They increase was for light transmission (or maybe a marketing ploy?) Later scopes from well known makers then started to get better adjustment. This was achieved by fitting the erector tube from a 1 in scope into a 30mm tube, Which would explain the current trend of 34mm and 40mm tubes. I suppose that there has to be a ratio for the diameter of the erector tube/outer tube to allow for the internal movement and therefore increased elevation.

 

[KY_Windage]

Around 30 moa is enough to get a lot of bullets to 1000 yds. I would say that if 40 is not enough you need to shoot a different bullet or put it on a different rifle.

 

[wedgy]

The idea is to be as close to the center of the lens(20 MOA up and 20 MOA down) when you are on target at 1,000 yards (if that is the range you are shooting at) because the glass is the sharpest in the center. You hear the term edge to edge clarity a lot. You can make it work but may not be able to zero at 100 yards, not a big deal. EGW will make any degree MOA rail you want.

 

[wkdickinson]

Use a good exterior ballistics program like "Shooter". Use the ballistics data of the cartridge you are using and calculate the drop from a 200 yd. zero (with a 20 MOA rail you can sight-in at 200 yds.). Then figure out how much internal adjustment your scope has and see if it is kind of in the center.

 

[Turbulent Turtle]

Question: What do you folks feel the MINIMUM amount of elevation scope adjustment is needed for say 1000 yards with a 20MOA angled base? All my current inventory are 60MOA+ total adjustment.

All the scopes I currently have include more than enough adjustment with a 20MOA base.

I am looking at a very rugged highly regarded fixed 25 power benchrest scope, but it only has 40MOA total adjustment.
I have a 20MOA base on all my long range rifles, but I'm concerned that ±20MOA still wont be enough? Or maybe close to maxing out?

If my math is right, even a 223 only needs about 35-40MOA for 1000 yards, and in theory knocking 20MOA off that with a base should make ±20MOA range marginally feasible. So many of the true long range cartridges require less than 30MOA total, so I think this range still works.

Id hate to buy it only to be disappointed.

Thoughts?

Here's the deal. A 40MOA total adjustment range is usually found in a one inch scope. Now, if all is perfect, when you mount the scope on the rifle, the mechanical zero of the scope happens to coincide with the scope being parallel to the bore of the rifle. You will burn about 3 MOAs to get to 100 yards and then another 34-40 for your putative .223 to 1000 yards. If you use a 20MOA ramp, and again the stars align, you will be pushing the erector completely against the wall. You will not be using the best part of the lens to look at your target and you will have zero to no wind adjustment.

You might want to look at a 30MOA ramp, or do what I do and use Burris Signature Rings along with a 20MOA ramp to bring the middle of the scope closer to the 1000 yard zero to take advantage of the best part of the lens and have the most wind adjustment.

The reason internal erector tubes are pretty much the same diameter regardless of the main tube because that dimension is linked to the size of the eyepiece and this the size of the human eye. I should think a whale would require a bigger eyepiece and internal tube in their scopes.