How Much Does the Height of Rings Affect Scope Elevation???

[sfldiver]

Just installed a Sightron SIII 1-50X60 to my Remington 700. I installed a 20 MOA base and Vortex/Seekins Pecision Matched Rings. I chose the high rings (1.26"), because I was looking for a bit more clearance under the end of the scope, so my mirage shield wouldn't hit my scope cap. My plan is to use this rifle for 600yd FTR, but my local practice range only offers 100yds.

When beginning the load development process last weekend, I found that I was unable to bring the bullet down to zero it at 100yds. The Sightron has 50 MOA vertical adjustment, so I should have 25 MOA to play with. The base used up 20 MOA of the 25, but is it possible the height of the rings used up more than 5 MOA?

I realized I can just zero it at 600, which will be my primary use, but I can also switch to a 10 MOA base and that should solve the problem, because I practice at 100 yards and that would be practical. However, I'm just trying to understand how much ring height affects scope elevation or if there's something else I'm missing?

Adrian

 

[XBBR Shooter]

Just installed a Sightron SIII 1-50X80 to my Remington 700. I installed a 20 MOA base and Vortex/Seekins Pecision Matched Rings. I chose the high rings (1.26"), because I was looking for a bit more clearance under the end of the scope, so my mirage shield wouldn't hit my scope cap. My plan is to use this rifle for 600yd FTR, but my local practice range only offers 100yds.

When beginning the load development process last weekend, I found that I was unable to bring the bullet down to zero it at 100yds. The Sightron has 50 MOA vertical adjustment, so I should have 25 MOA to play with. The base used up 20 MOA of the 25, but is it possible the height of the rings used up more than 5 MOA?

I realized I can just zero it at 600, which will be my primary use, but I can also switch to a 10 MOA base and that should solve the problem, because I practice at 100 yards and that would be practical. However, I'm just trying to understand how much ring height affects scope elevation or if there's something else I'm missing?

Adrian

The rings didn't "use up" any elevation (IF they were made properly).
But receivers are not perfect on their outside dimensions. The front of the 700 is a cylinder, but the rear is lower than the cylinder - it is cut down then hand polished - a variation of 1/100th" is enough to eat up your needed elevation.
Try a pair of Burris high Signature ZEE rings - they'll solve your problems for ~ $39.

 

[Auto-X Fil]

You should only need 15 MOA to get to 600, so there's not really any reason to use a 20moa base unless you want to be ready for 1,000yd. In either case, 20moa is too steep of a base for a scope with only 50moa of adjustment. As noted, you need some amount of adjustment just to zero the rifle to account for scope/mount/receiver/barrel mis-alignment.

As far as your specific question, raising your scope by 1.0472" will require 1MOA more adjustment... the math is the same as moving the bullet on the target. So the rings have almost nothing to do with it.

Your scope is probably 2" above the bore, and the bullet drops something like 1.5-2.0" on the way to 100yd. So that's nearly 5moa of extra slack that should let you zero. Either the reciever or mount or rings are not very well-aligned.

A 10moa rail would get you zeroed at 100, and give you 40+moa of travel, which is enough to get you to 1000yd, although you might get limited in your windage travel and have a poor sight picture with that much elevation dialed in.

If you're only shooting 600yd, just buy a 0MOA base and be done with it.

 

[HTSmith]

Adrian I have the same scope also with a 20 moa base. No problem zeroing at 100 yards. I do have the Burris signature z rings as suggested above

 

[savagedasher]

Ring hight change The amount the base gives you. The closer to bore the more

Adrian I have the same scope also with a 20 moa base. No problem zeroing at 100 yards. I do have the Burris signature z rings as suggested above

If you want to keep your scope centered 10 to 15 moa base is correct depending on ring height . Larry

 

[Ned Ludd]

You can play around with scope height above the bore at a ballistic calculator such as JBM to see what the effect of different ring/scope height will be:

http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi

Here is the output with the scopes heights set to 2.19" and 1.3", respectively:

Because the height between the bore and the centerline of the scope is different, the drops will also change. The difference is not huge, but there nonetheless. The flatter the trajectory of your chosen cartridge, the less the effect will be. Not sure if the difference would be enough to allow you to zero at 100 yd. I've never had a problem zeroing scopes mounted on 20 MOA bases that have less total elevation travel than yours, but I have seen occasional posts by others that have.