Rifle scope question

R

RAfiringline

New member
I have an AR that I bench zero'd in at 100 yds, about 11 weeks ago. I got good groups over and over - no reason to doubt the scope.

Since then, I've been practicing offhand shooting at 100 feet -same rifle and scope and no adjustment to the scope - I want to keep a 100 yd zero and just adjust sight picture to hit where I want at shorter distances.

I was getting suspicious something was off, so yesterday I went back to the 100 yd range bench and shot a 3 rd. group, using the same ammo I previously used to zero the rifle.

The group was nice: 0.85". The only problem was that it centered 9" right and 6" low to where it was supposed to be!

I frequently check the scope mounts and they're always tight w/ no loosening. I don't bang the rifle around, it sits on a couple foam pads to and from the range.

At this point I should own up that it's a $30 Ncstar scope - not a $300 Nikon.
That admitted, what the hell is going on with this thing?
Consistent tight groups - lot's of them, and then it shifts like this???
 
A $30 Ncstar might be the issue. Might not though. Sometime the ammo can be temperature sensitive.
Anything weird about the rifle stock, etc?
 
At this point I should own up that it's a $30 Ncstar scope
Click to expand...

I have no doubts that this is your problem. A decent scope starts at about $200 MSRP. You might find something on sale for less, but I can't think of a single scope much under $200 that I'd trust.

On an AR for all around use this is my 1st choice

http://swfa.com/Leupold-1-4x20-VX-1-ShotgunMuzzleloader-Scope-P51851.aspx

On 1X it is faster for up close shooting than the irons, 4X is enough magnification to get you to at least 300 yards.

If you want more magnification these are good scopes too.

http://swfa.com/Leupold-3-9x40-VX-1-Riflescope-P51827.aspx
http://swfa.com/Burris-3-9x40-Fullfield-II-Rifle-Scope-P7932.aspx
 
>A $30 Ncstar might be the issue. Might not though. Sometime the ammo can be temperature sensitive.
Anything weird about the rifle stock, etc?<

I've been using Geco 55g, which I've grouped with nearly as tightly as Fed Gold Match which is 3x as costly.

I did do most of my bench shooting a few months ago in temperatures of 80s and 90s. Yesterday, my 3 shot group was at around 60F.

Everything on the rifle has stayed the same - the stock is just a standard adjustable. This is just a $500 DPMS Oracle, out of the box.

If the groups had widened way up and also shifted center, I'd blame it on the scope and replace it. But I've always been getting nice .8" to 1.7" bench groups with this rifle-scope-ammo "system", and it's just not coming to me why it would do this with no messing w/ the adjusment screws.
 
On some of the budget scopes I have had, when adjusting them the erector on the inside would bind, turn the knobs and the poi would not change, then turn some more and it would move 3x more than expected.

I have gotten where after I do a adjustment now, I tap the turrets in a effort to release any binding.

Now on my leupolds, ior's, vortex vipers, it is not a issue.
 
The greatest single problem (aside from poor glass) with budget scopes is consistency. You may get several excellent groups after zeroing, only to find that the next time out, the zero has wandered. Exactly as the OP describes.

If the rings and mounts are good and solid.....and there is no other mechanical cause (anything allowing movement in the system)....then the problem MUST be the scope. Unfortunately, you can't expect much from a $30 scope......and that is what you are getting.

Upgrade the optics. With optics, you DO get what you pay for. An overused cliche, yes, but very, very true. This doesn't mean that you must spend $3000.....but you do need to spend enough to get actual quality.
 
Scope: Simmons Whitetail Classic featuring 2X - 8X settings. It holds its zero each and every year that I've owned it and is not affected by extreme cold.

Jack

 
At this point I should own up that it's a $30 Ncstar scope
Click to expand...

Given that you are still getting good groups, I'd give it another chance.

The chance of having a budget sub MOA carbine with a $30 scope can't be passed up.

Is it a fixed power scope, 4x30, 6x42? If not, were both bench test conducted at the same power?
 
" A decent scope starts at about $200 MSRP. You might find something on sale for less, but I can't think of a single scope much under $200 that I'd trust"

Fortunately, there are MANY under $200 scopes that are very functional and suitable for most shooters' needs.

"Sightron's makes a 3-9x40 that is less than $100 on optics planet."

Good choice here.
 
>Given that you are still getting good groups, I'd give it another chance.
The chance of having a budget sub MOA carbine with a $30 scope can't be passed up.
Is it a fixed power scope, 4x30, 6x42? If not, were both bench test conducted at the same power?<

It's a small diameter 2-6x28, and all the distance shooting was done at 6x.
For this rifle, I wanted a short scope w/ a small diameter.

Here's six 5 shot groups at 100 yds:

http://thefiringline.com/forums/attachment.php?attachmentid=98986&d=1431466830

The targets in the below pic show 200,300,400 yard shooting.

http://thefiringline.com/forums/attachment.php?attachmentid=99843&d=1439941976

I can afford to spend lots on my gun hobby, but I get a kick out of good results for minimum expense - I think you can see why I like this set-up.
 
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So now it seems as if there is no problem. Somehow, I think this thread was a setup - in that the OP was planning to "spring" his photos of good results on us, after everyone commented, based on the apparent zero shift problem he had with his fine, $30 Chinese scope. I tend to suspect that the pictured groups were not actually shot with the scope in question, or at the distances claimed. Just a suspicion.

If the $30 scope works for you, more power to you.

However, if you have a zero shift for no apparent reason, with it not traceable to such things as ammo, loose mounts, etc.....then the cause is the SCOPE. That's all it can be. Unless, perhaps, your aim was off....consistently for the entire group. Not likely. The erector mechanism in that fine scope simply shifted, as does happen with cheap scopes.....but it happened to "stick" at the same position, thus producing a good group, but shifted away from the point-of-aim. Usually when the mechanism shifts in such scopes, they spray bullets all over, because the mechanism does not hold the same position. Yours happened to "stick". THIS time. Next time, it may do the same thing - only shift 9" to the left and stick there for awhile. Or, it may start bouncing around and thus spraying bullets all over.
No way to tell.

The bottom line is - you can't really trust a scope like that, can you ?

Nevertheless, if you don't see the logic in the argument, no problem. "No skin off my nose", as they say. Hopefully, your fine $30 Chinese scope will continue to work well for you. That will certainly save you a lot of money. I'd love it, if such a thing happened to me. But, it never has. Every time I've ever bought a cheap Chinese scope, I've been disappointed. I did buy a few, when I was younger and much poorer.

But I learned.
 
>So now it seems as if there is no problem.<

That's pretty stupid.
In the first post, I stated the scope worked fine, still shoots a tight group, but has shifted the center of the group substantially.
That was the problem I was asking about.

>Somehow, I think this thread was a setup - in that the OP was planning to "spring" his photos of good results on us, after everyone commented, based on the apparent zero shift problem he had with his fine, $30 Chinese scope. I tend to suspect that the pictured groups were not actually shot with the scope in question, or at the distances claimed. Just a suspicion. <

That's even more stupid.
The pictures have been posted in other threads on this forum going back to mid May, 2015 - they weren't "sprung".

Enough.
 
I get a kick out of good results for minimum expense - I think you can see why I like this set-up.
Click to expand...

I have scopes cheaper than your NCStar that work well and never shift. I get the same satisfaction out of using those as I used to get from using a Ruger 345 to outshoot pricier 1911s. The expensive stuff should always be flawless, but getting a good result on a miniscule budget is it's own kind of satisfaction.

I think lots of mischief can hide in the variable magnification mechanism, so I try to stay clear of variable power scopes. I am currently tempted by the prospect of trying an NCStar 6x42.
 
zukiphile:

>I think lots of mischief can hide in the variable magnification mechanism, so I try to stay clear of variable power scopes. I am currently tempted by the prospect of trying an NCStar 6x42.<

Maybe the variable thing is the cause.

This 100 ft offhand shooting I've been doing (since zeroing at 6x) is at 2x, and what made me suspicious about the scope was that I was having to use a way high-left sight picture to hit around where I wanted. All the shooting I had done with the rifle prior to the offhand stuff, was at distance w/ 6x.

Maybe a good test would be to re-zero at 6x at 100 yds, then dial down to 2x and see where the group centers. If it centers as it should, dial up to 4x, 6x, and verify it holds centers up and down.

If it doesn't hold center for all powers, or changing power louses up center, the scope is worse than useless and it gets trashed.
It hasn't occurred to me that changing power would louse up the group center.
What do you think, zukiphile?
 
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If it doesn't hold center for all powers, the scope is worse than useless and it gets trashed.
Click to expand...

I don't think it is worse than useless. I think a zero that shifts with magnification is a cheap scope problem that the attention to detail and better engineering makes less likely in an expensive scope.

In your position, if I had a scope that held zero so long as it were left at the same power, I would pick the power I liked and leave it there.
 
>I don't think it is worse than useless. I think a zero that shifts with magnification is a cheap scope problem that the attention to detail and better engineering makes less likely in an expensive scope.
In your position, if I had a scope that held zero so long as it were left at the same power, I would pick the power I liked and leave it there.<

Weather permitting, I'm going to range test it Thursday.
If it can't hold the same COI at various powers, or if changing powers somehow alters COI (which could explain what I've experienced), I have no use for it and I'll start researching for something reliable up to $300 or 400.

My hope is that even though I always tap the scope repeatedly after click adjustments, it just didn't get all the way adjusted after I last 100 yd zero'd it, and the subsequent shooting jolted it enough to throw the COI off, a lot.

Anyway it goes, it's a good excuse to do some shooting.
 
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