Scopes holding zero?

[Scoundrel]

I have a few low end scopes (Barska, NCStar) and a couple rifles that I put them on. I've tested them out mostly at 25 yards with targets that have 2" circles.

One has a quick release weaver mount. Every single time I went to the range with it, I had to re-zero it. I figured it was because it was a quick-release and I kept removing it and putting it back on.

So, I tried again with the rings mounting to a riser, and made sure that every single damn screw was as tight as I dared crank it. I still have to re-zero the damn things every time.

In one case, I was asked to move from one bay at the shooting range to another one, to make room for an event. I bagged the gun and moved. When I got to the other bay, it had lost zero - but everything was tight! WTF?!

Does it have anything to do with the fact that they have variable zoom ranges on them? I don't remember them needing to be re-zeroed in the same range session when shifting from 3x to 9x zoom.

How are people getting these scopes to hold zero?
Are my low end scopes inherently flawed?
Do I have to pay $300 for a scope to get one that holds zero?

[les strat]

Is this rimfire or a higher caliber rifle?

Quick release mounts are inherently bad about not holding zero unless you spend big bucks on them. Even then, they will still only say "within 2 MOA" at best. If I had a scope zeroed, I wouldn't take it on and off.

Although cheap scopes are not going to be anywhere near as ruggedly built as Nikon-Leupold-Zeis counterparts, any scope is only as good as the rings and base(s). Get a weak link there, and none of them will hold zero. Steel bases and rings, like Leupold, etc, are your best bet for holding zero. Use a little loktite or clear nail polish on the base screws. There are also methods of lapping rings that make for a better fit with the rings and scope tube.

I have a Simmons .22 Mag scope in my Marlin M60. Great scope for the money and holds zero. I wouldn't think of putting something in that price range on my deer rifle though. The old saying with hunters is you usually spend as much or more on your glass as you do the gun.

[yqtszhj]

I spent $80 on some quick release rings for a $180 Leupold 3-9 power scope and I can remove the scope and place it back on my AR and it keeps dead zero at 60 yards.

I would bet it's something with the rings or the way mounted. It's tough to get it exactly right but when you do it will hold the Zero IMO.

[CJB]

I have a few low end scopes (Barska, NCStar) and a couple rifles that I put them on. I've tested them out mostly at 25 yards with targets that have 2" circles.

One has a quick release weaver mount. Every single time I went to the range with it, I had to re-zero it. I figured it was because it was a quick-release and I kept removing it and putting it back on.

So, I tried again with the rings mounting to a riser, and made sure that every single damn screw was as tight as I dared crank it. I still have to re-zero the damn things every time.

In one case, I was asked to move from one bay at the shooting range to another one, to make room for an event. I bagged the gun and moved. When I got to the other bay, it had lost zero - but everything was tight! WTF?!

Does it have anything to do with the fact that they have variable zoom ranges on them? I don't remember them needing to be re-zeroed in the same range session when shifting from 3x to 9x zoom.

How are people getting these scopes to hold zero?
Are my low end scopes inherently flawed?
Do I have to pay $300 for a scope to get one that holds zero?

Couple of problems....


First, you cannot "test" them at 25 yards, because parallax can move your point of am a few INCHES at that distance, depending on how your eye is lined up at the back of the scope.

'Nudder thing, is unless the mount is truly rigid, like on a bolt action rifle, expect shifting. The AR mount is held to .5000" to .5005 <--- one half of one onethoundanth of an inch. Thats it. Normally precision barstock will "just fit" into the mount. But... thats left/right. The up down rides on less precise angled areas. There is a LOT of variation in how the mounts sit in those, or rather "on" those angled areas. The best bet is to relieve the mount so you have front and rear contact areas with the rest "floating" on the mount. Few mounts do that. Those that do, also need a way to secure the mount without flexing things - because now you've introduced problems with that. All of the preceding was for the traditional "handle" mount. Rail mounds are more secure, more repeatable - but not all mounts fit all rails very well. There is a LOT of variation there.

M-14 and Mini 14 mounts generally suck pretty bad. You can whisper next to them and they'll shift some.

The trick with parallax is to not "full field" the picture at the back of the scope, but move your eye closer (watch out for heavy recoil) until there is a dark ring, with a visible picture centered around the crosshairs. When you do that, you've eliminated parallax to an amazingly large degree - its all "on axis" that way - and the errors are down to a very low level.

[Scoundrel]

The rifles are an AR-15, a 15-22, and a Charger 10/22 pistol which is basically a shortened 10/22 rifle.

All three user weaver/picatinny rails (the Ruger has a dual setup that can accept either the weaver/picatinny stuff or something else).

I do try and make the picture close to full field, but still where I can see the edges of the circle with black around it. I definitely noticed when I made the picture too big that my eye kind of "got lost" and things got weird in there visually.

Fortunately recoil is not an issue for me with these calibers and action types.

I have been wanting to get to an outdoor range and try these things at more than 25 yards, but I'm still working on holding things steady, and have only started to have good groups at 25 yards. Not really ready for 100 yards yet, and the nearby outdoor range master has a serious attitude problem.

From the above posts, it sounds to me like my best option for the zero problem is to throw my $6 NCStar rings in the trash where they belong and get me some good rings, and do some research on making those rings fit the scope well.

But, at short range, I might not be able to keep a good zero just due to how the optics work, because it's not just the scope, it's where I put my eyeball.

I do have one question about that: Why wouldn't the eyeball placement/parallax produce the same problems at longer ranges? Obviously I do not know much about these things, but I would expect the problem to be amplified the further the the target was from me.

[CJB]

I do have one question about that: Why wouldn't the eyeball placement/parallax produce the same problems at longer ranges? Obviously I do not know much about these things, but I would expect the problem to be amplified the further the the target was from me.

The problem of "parallax" exists at all ranges - except - the range at which the scope is corrected for. What is actually being corrected, is the optical placement of the crosshairs onto the same distance as the target.

http://upload.wikimedia.org/wikipedia/commons/a/ab/Parallax.gif

From Wikipedia - see how close objects appear to move horizontally more than distant ones? Parallax. Thats why the scope is not "magnifying" it at long range. The optical design of a center fire scope usually places the crosshairs at about 100 yards/meters or so ( maybe more ). Rimfire scopes are corrected for shorter distances - maybe 25yards/meters.

Scopes with adjustable objective lenses allow two things - better focus at close range, and parallax correction at close range.

BUT - the eye is a wonderfully accurate comparator, given the right situation. IF you crowd your eye so that you get mostly black, just a bit of image around the crosshairs - your brain/eye/muscle's feedback loop will damn near "auto correct" the sight picture to center that little circular image onto the crosshairs. Keep that image centered as you also align with the target... and you've got the scope almost totally on its optical axis, and parallax is eliminated. That can only be done with smallbore and rimfire - as you've pointed out you have - so that you don't whack your own eyeball with the scope.

Make more sense now?

[Scoundrel]

More or less, yes.

These are the scopes I have:


NCStar STP3942G 3-9X42 Compact-Red and Green Illuminated P4 Sniper/Green Lens/Quick Release
http://www.ncstar.com/scripts/prodView.asp?idproduct=39

BARSKA AC10552 3-9x42 IR Contour Dual Color Reticle 30/30 IR Riflescope
http://www.barska.com/Contour_Rifle_Scopes-BARSKA_3-9x42_IR_CONTOUR_SCOPE.html

Not sure if these are considered rimfire or centerfire scopes. The websites don't really say, although in the specs, they say something about 100 yards when indicating the field of view, so that seems to imply that these are intended for use at that range. Also, the NCStar has a bullet drop compensator calibrated for the .223 (which also implies that it is a "centerfire" scope), and I don't imagine they'd have one of those on a scope that was intended for use at 25 yards.

NCStar: FOV (FEET AT 100 YARDS) 36.8-12.0
Barska: Field of View (ft@100yds/m@100m) 36.7/12.3@3x, 12.5/4.2@9x

So I guess I'd better get out there and dial in the scopes at 100 yards, then go home and go again the next week before I decide that they're not holding zero. Then decide whether I need new rings.


I know the movies are full of crap and all of that, but I see these movies where these guys unpack a rifle out of a suitcase, assemble it, and the scope is perfect, and I think to myself, "That's a bunch of crap, I'd have to zero it in again." But I'd sure like to be able to do that.

[les strat]

There again, those "lego" rifles and scopes units are precision intruments.

My Eotech has a quick release mount and wasn't cheap. It is supposed to hold a 1MOA zero if removed and remounted. Now that it is sighted in, I'm not touching it.

I guess I am old school. Once we had our hunting scopes mounted properly and zeroed, we left them alone and tried to keep from knocking them at all. I still do that.

[Scoundrel]

There again, those "lego" rifles and scopes units are precision intruments.

My Eotech has a quick release mount and wasn't cheap. It is supposed to hold a 1MOA zero if removed and remounted. Now that it is sighted in, I'm not touching it.

I guess I am old school. Once we had our hunting scopes mounted properly and zeroed, we left them alone and tried to keep from knocking them at all. I still do that.

For a while, when I was still fiddling with different scopes and stuff, I moved them around from one gun to the other quite a bit. I've settled down on that, and have nice padded cases for them all now that allow me to leave the scope on during transport. So perhaps I will use some loc-tite and more or less permanently mount them.

But before I do that, I wanted to find out whether the mounts I have would do the job or whether I needed to replace them (so I'm not really done fiddling yet).

But then again, a few weeks ago we took the AR-15 shooting, and our targets were fairly close in. I flipped the quick release and removed the glass so we could use the flip-up Magpul sight. So...