Rifle Scopes Zeroing a scope at the top of elevation adjustment range bad?

[RyeDaddy]

Curious whether it's bad to have a scope that's zero'd outside the middle of it's adjustment range?

Let's say I have a quality scope (Nightforce) and I mount it on a rifle with a 40 MOA base. If a 100 yard zero leaves me with 24 mils up (out of a max of 27) is this a bad thing?

I've read on the error-net that it's best to have a scope zero'd in the middle of the adjustment range, but not why or what the downside of not doing that is.

Not knowing the internal mechanics of a scope very well I'm not sure if one might damage a scope by having it sit at the outer edges of adjustment for long periods or anything. Or might it be because some scopes don't track as accurately toward the edges?

 

[Temp9]

Having tons of up adjustment is generally considered beneficial on this forum. The only problem with zeroing near the edges of the adjustment is... well, the lack of adjustment in that direction. I've heard people say that image quality reduces towards the edges of the erector travel (adjustment range), but I haven't noticed that myself.

 

[billyburl2]

A scope as robust as a NF, I wouldn't sweat it. Other scope might have some issues. You might experience some degradation of the sight picture, such as chromatic aberration, or flaring. The optics will always be better if the erector tube is centered between the objective and ocular lenses.

All this begs the question, what is the scope mounted on? And are you going to use the 24 mils of "up" you have? It might be better all around if you went to 20MOA rail...

 

[RyeDaddy]

Ah, I hadn't thought about image quality.

No, I don't need all that elevation. The scope will be moved back and forth between two rifles, one of which is a flat top AR I've been using the scope on, the other a bolt action with a 20 MOA base that's being built right now. So what I'm really asking is if I leave the scope in the 20 MOA unimount it's currently mounted in will it be a problem on the bolt gun with a combined 40 MOA of cant. If so, I'd need to sell the 20 MOA unimount and get a Badger 22 MOA riser for the AR and a regular set of rings for the scope.

 

[Pinecone]

Another thing to consider is, that near the ends of the elevation travel, the windage travel is limited.

But how much windage do you need at 100 yards? And how often will you get shooting at 100 yards versus at longer ranges where you will be closer to the middle?

 

[dieselten]

Ah, I hadn't thought about image quality.

No, I don't need all that elevation. The scope will be moved back and forth between two rifles, one of which is a flat top AR I've been using the scope on, the other a bolt action with a 20 MOA base that's being built right now. So what I'm really asking is if I leave the scope in the 20 MOA unimount it's currently mounted in will it be a problem on the bolt gun with a combined 40 MOA of cant. If so, I'd need to sell the 20 MOA unimount and get a Badger 22 MOA riser for the AR and a regular set of rings for the scope.

Or just get a flat rail on the bolt gun

 

[RyeDaddy]

I had thought of that, but it's a Badger M2013. I can call Badger Ordnance and see if they sell flat rails for their actions I guess.

Or... I could just buy another scope, problem solved. Ha!

 

[BCP]

Curious whether it's bad to have a scope that's zero'd outside the middle of it's adjustment range?

Let's say I have a quality scope (Nightforce) and I mount it on a rifle with a 40 MOA base. If a 100 yard zero leaves me with 24 mils up (out of a max of 27) is this a bad thing?

I've read on the error-net that it's best to have a scope zero'd in the middle of the adjustment range, but not why or what the downside of not doing that is.

Not knowing the internal mechanics of a scope very well I'm not sure if one might damage a scope by having it sit at the outer edges of adjustment for long periods or anything. Or might it be because some scopes don't track as accurately toward the edges?

I've read that having it maxed out all the time can wear out the springs and make adjustments less accurate.

Not sure if I buy the argument or not but I did read it on here and the person who posited it also claimed to "fix scopes for a living".

 

[PeterPHWS]

You can do a bit of common sense preservation of the springs in the scope by storing it in the cabinet at mid travel if you have a high incline rail.

Then just dial it down to your zero when you bring it out to play.

 

[Tarheelpwr]

I've read that having it maxed out all the time can wear out the springs and make adjustments less accurate.

Not sure if I buy the argument or not but I did read it on here and the person who posited it also claimed to "fix scopes for a living".

Vortex optics told me the same thing. It makes sense. If you keep a spring maxed in either direction, Hooks law will define how it fatigues.

 

[E. Bryant]

If you keep a spring maxed in either direction, Hooks law will define how it fatigues.

Hooke's law is F = kx; I don't see any term in there for the time, so that particular equation really doesn't care how long the spring is compressed.

Any spring worth a damn will not plastically (permanently) deform at any reasonable temperature. Keep 'em compressed for as long as you want; it won't hurt anything.

 

[RyeDaddy]

Thanks guys. I had thought I read somewhere around here about the springs wearing out and wasn't sure if I just imagined it. Other people seem to have heard the same thing so I won't do that just in case. I'll just end up buying another scope so I don't have to futz with it.

 

[Pinecone]

From the same guys who tell you if you leave a magazine loaded for more than a few months, the rounds won't feed due to the spring being destroyed.

I left some Wilson magazines loaded for over 15 years, and they are fine.

 

[RyeDaddy]

That's true, my AR mags have been loaded for years and still function perfectly when I take them out.

As an aside I have seen one Glock 23 mag that wore out. It was my father in law's and had been loaded for who knows how long. More than 10 years I'm sure. He finally decided to shoot the mag he had been carrying around for so long and it failed to chamber multiple times. Pushing on the follower with your finger it was obvious it didn't have near the resistance that any of our other mags do. He called Glock and they had him send the whole package in and replaced all his mags and every single part on the pistol other than the barrel, frame and slide including putting new night sights on it. He's a cheap old bastard, I would've just bought a new mag.

I don't think I'd end up swapping a scope between rifles for eternity, but probably will have to for a short while. I have a pile of money I've saved that I'm itching to spend on a new scope for the Badger when it shows up next month but gotta sit on my cash till the government shutdown shit ends and the paychecks start coming in again.