Lack of Adjustment in Higher Power Scopes

[Catpop]

I know I probably should know this, but I'm not really up on scope construction.
Question: Is the higher the power, 3x9 vs. 6x20, equate to the lesser amount of adjustment available , ie stop to stop turning the knobs.
Reason I ask, I just purchased a 6 x 20 Redfield scope and I'm having a devil of a time dialing it in. It will not give me the amount of adjustment I need to bring poi to poa. Of course the fact it is on a Ruger with integral rings isn't helping at all as there is no way to really get windage and elevation adjustment from this system.
Any ideas?
Thanks, Catpop

 

[Snyper]

The magnification range has little to do with windage and elevation adustments

I suspect your mounts aren't lined up correctly

 

[buckhorn_cortez]

The size of the tube limits the amount of adjustment, as the scope erector system is generally scaled to the size of the tube. Smaller tubes have smaller erector systems with less adjustment.

That's why you'll find larger tubes (34mm, 35mm, and 40mm) on the higher end rifle scopes - they allow the erector system to be larger with more adjustment. Another benefit of the larger tubes is that they allow bigger objective lenses that let in more light.

If you are having trouble with the elevation on rifles without integral rings you can get rings or bases with a built-in angle adjustment of 10 MOA, or 20 MOA so that the scope is already tilted downward toward the muzzle before you start making further adjustments.

If you're running out of windage adjustment - then the scope is out of alignment.

If you're running out of elevation adjustment and the rifle has integral rings - don't have a solution for you.

 

[MEHavey]

Ruger rings are of different height front/rear.
Might reversal of that difference be your problem?

See: http://www.24hourcampfire.com/ubbth...r/13858/filename/Ruger Scope Ring Diagram.jpg

 

[Catpop]

Really? I'll check. Thanks

 

[jmr40]

If he had the rings reversed on a Ruger it should be pretty obvious. I don't see how you could mount a scope without breaking it with the rings reversed.

 

[MEHavey]

I don't see how....

One might think..... and yet....
https://www.youtube.com/watch?v=gM7JKQJoUgQ

 

[Catpop]

Looks like MEHavey hit the nail on the head. They are 2 different heights, which should have been obvious. BUT and there is always a BUT, I was using the Redfield Ruger M77 rings to mount on a mini 14. An in my haste to get it on and make it to the range, I didn't catch the difference. Had it not been for MEHAVEY's post, I would have continued with my effort to make a ring shim. I had another set, so I just took the other high ring from it and now all is well.
Thank you MEHavey!
Catpop

 

[MEHavey]

De nada señor.
With three different Ruger M77s... been there scratching my head before. v

 

[Catpop]

Update 4-17-15

Ok, I got the ring height problem solved thanks to MEHAVEY and took another trip to the 100 yard range. But still had problems.
Best I could adjust poi at 100 yards to poa was 12" high and 4" to left. I adjusted my poa so I could continue with 3 shot group load testing on my mini 14.
Back at the shop I said this problem between the 6 x 18 scope and the non adjustable Ruger integral ring has got to be solved and without spending another 50 - 75 dear ones.
So here's how I solved the problem.
First I put the scope's elevation and windage adjustments in the center.
Windage was handled by filing a small amount off the ring recoil lug so I could shift the axis of the scope tube.
Elevation was a little more complicated. I put a paper strip in the bottom of the front ring. Not enough so I put another finally ending up with 4 strips. Just right. Then I took some saran wrap and put in the bottom of the ring, followed by an epoxy putty I use u/w for boat repairs, followed by another layer of saran wrap. It was then snuggled up and allowed to cure. After curing I removed the new cast spacer and dressed it up a tad. Then remounted the scope and took it out for a test.
Dead on! Now my scope is on and with maximum adjustment in any direction.
Lack of adjustment problem solved. Maybe this will help others.
Thanks Catpop

 

[bush3755]

Some receivers have their barrel axis quite misaligned with the scope rings axis mounted on them.

Another issue is most scopes of higher power have less adjustment range. The larger images they make at the reticle plane means there's less image area on them for the mechanics to move the reticle. Compare scope's specs for adjustment range versus magnification and you'll see the difference.

Most of the time, only half the elevation adjustment range of scopes is usable if their mechanical center axis is parallel with the bore axis. You'll need an angled base (10 to 30 MOA) to enable higher magnification scopes to be used at the longer ranges.

 

[Catpop]

Bush 3755,
Lack of adjustment was the original purpose of this post. But I've a lot more just reading post like yours.
By the way, I made my own scope shims to over come this angle
delimma.
Tx catpop

 

[bush3755]

Catpop.

There's another reason that a scope may appear to be misaligned with the receiver axis. It happens when the popular method of zeroing the adjustments believed to center them so the reticle will be centered on the scope tube axis. That is putting each one at the middle of their range.

While that's what a lot of people do, it rarely centers the reticle in the scope 's outer tube and the main optical axis from objective lens to eyepiece lens centered in the main tube. That's because a lot of scopes have more adjustment range from its optical/mechanical zero towards the adjustment turret knobs. After putting the adjustments mid point in their range, then laying the scope in a set of V blocks (or rings slightly loosened so the scope can be twisted in a circle), turning the scope and looking through it will show the reticle center making a circle about some point. Adjusting the knobs so the reticle stays at the same place as the scope's twisted in a circle puts the scope's inner tube of lenses (and the reticule in rear focal plane ones) in line with the objective lens to eyepiece axis as well as the tube axis.

3/4" diameter tube scopes can have the same adjustment range of larger tube ones. While their physical range of adjustment is less than 1 inch or 30mm tubes, their lenses have shorter focal lengths which makes the images at the two focal planes smaller. So the reticle can have the same angular adjustment range as larger tubes