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When to consider a scope defective

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/29/2017 at 11:52
dbooksta View Drop Down
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I've learned the hard way that it's important to run a battery of tests on scopes as soon as I receive them, and occasionally as time goes on.  But I'm not sure what the acceptance criteria should be for some of these:
  1. Return-to-zero: Dial elevation and windage to extremes, then back to their starting point.  If the reticle doesn't return to its initial point exactly, reject?
  2. Reticle cant: Align reticle with a straight edge and dial elevation.  If it deviates left or right from the edge the reticle is canted with respect to the adjustments.  Reject for any cant, no matter how small?
  3. Click calibration: While sighting on a calibration target (i.e., verified marks at verified distance), dial elevation and windage.  Typically we have 1/4MOA or 1/10mil clicks.  How much deviation from the indicated value should be allowed before rejecting?
  4. Click consistency: If the reticle adjustment effected by a click varies at all across the adjustment range, reject?
  5. Parallax (if the scope has a parallax adjustment): Dial parallax to bring a target within focus, then move the eye off-axis.  If the reticle moves at all with respect to the target, reject?
  6. Focus: If a flat target oriented perpendicularly to the scope cannot be kept in focus across the full field of view, reject?
  7. Reticle accuracy: If the reticle marks do not perfectly correspond to the specified angles, reject?  (For SFP reticles, this would be a reject only if they do not correspond at any magnification that can be dialed.)
  8. Recoil resistance: Assuming the scope is securely mounted: Dial the reticle, check its center, then slap the scope (without moving whatever it's mounted to at all).  If the reticle moves at all, reject?
I assume that absolute perfection in the above measures can be expected from top-of-the-line scopes (i.e., $2k+).  But I suspect that not allowing any errors in these tests with many scopes would be unrealistic.  (I.e., one could test every scope coming off a production line and not find a single one that satisfies, or can be repaired to satisfy, all of these.)  So how much allowance should be granted and at what levels?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/29/2017 at 12:03
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Interesting questions.

I am very curious to see what the responses to this will be.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/29/2017 at 13:49
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I'm not sure "mechanical" and "perfect" go together in the same sentence, at least not perfect "perfect."

Lower limits of detection are a reasonable line, "perfect" is a stretch.

I have match barrels with thousandths of an inch of run-out, they are not technically perfect, but are just above the limits of what I can detect.  That said, they outshoot me constantly.

As a general rule, if there is a problem I can detect, then there is a problem.  

Kinda reminds me of all the Leupold owners telling me their turret adjustments are perfect, then tell me they don't twist turrets anyway.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/29/2017 at 20:55
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I think perfection is too high a standard. It would require a very consistent cheek weld and a absolutely solid mount. That doesn't move at all to rule out movement of the scope.

If #5 occurs I would think it is operator error and not a scope issue.

For me #6 would not be an issue since I am not aiming at the edge of the FOV. The reticle isn't there. Even if I am using extreme Kentucky windage.

#7 I think you are referring to a FFP scope not a SFP scope. SFPs are only calibrated at one magnification setting.

With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 04:18
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Originally posted by Sparky Sparky wrote:

I think perfection is too high a standard. It would require a very consistent cheek weld and a absolutely solid mount. That doesn't move at all to rule out movement of the scope.

If #5 occurs I would think it is operator error and not a scope issue.

For me #6 would not be an issue since I am not aiming at the edge of the FOV. The reticle isn't there. Even if I am using extreme Kentucky windage.

#7 I think you are referring to a FFP scope not a SFP scope. SFPs are only calibrated at one magnification setting.

With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.

That would be considered some sort of assault, anyway...  "scope abuse"... can't have that... you should never slap your scope under any circumstances...

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 09:06
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Originally posted by Kickboxer Kickboxer wrote:

Originally posted by Sparky Sparky wrote:

I think perfection is too high a standard. It would require a very consistent cheek weld and a absolutely solid mount. That doesn't move at all to rule out movement of the scope.

If #5 occurs I would think it is operator error and not a scope issue.

For me #6 would not be an issue since I am not aiming at the edge of the FOV. The reticle isn't there. Even if I am using extreme Kentucky windage.

#7 I think you are referring to a FFP scope not a SFP scope. SFPs are only calibrated at one magnification setting.

With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.

That would be considered some sort of assault, anyway...  "scope abuse"... can't have that... you should never slap your scope under any circumstances...

Or your wife or girlfriend.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 11:55
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Originally posted by Sparky Sparky wrote:

If #5 occurs I would think it is operator error and not a scope issue.

Ilya at least once wrote that condition #5 is a sign of something amiss in a scope's internals.  I didn't realize this is in dispute.  Should I post as a separate question?  "If you can't dial out reticle parallax (beyond the scope's minimum adjustment range, which in every scope I've seen is no further than 50 yards) and simultaneously have the target in focus, is this an indication of a opto-mechanical defect, or a user error?  If user error, how is it corrected?"

Originally posted by Sparky Sparky wrote:

#7 I think you are referring to a FFP scope not a SFP scope. SFPs are only calibrated at one magnification setting.

Right: On a SFP scope there is a magnification at which they are supposed to be calibrated.  Maybe they don't nail the calibration at that exact magnification, but if you can't adjust the magnification to bring the reticle into calibration at any point I would consider that to be a problem!

Originally posted by Sparky Sparky wrote:

With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.

True, I expect a bare-handed blow to be less demanding on the erector spring(s) than even middling recoil, but when it does cause a reticle shift ... well, I just returned a scope for repair because it failed this test! 

The only other way I can imagine to detect recoil shift is to simultaneously mount a second scope to the same gun, then shoot it.  If the reticles diverge, then you know at least one scope is bad, but then you have the problem of figuring out which one....

Or are there other reliable tests for this?
Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: August/30/2017 at 12:45
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I consider it defective when it say's...Barska on the box. Big Grin 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 12:49
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Originally posted by 3_tens 3_tens wrote:

Originally posted by Kickboxer Kickboxer wrote:

Originally posted by Sparky Sparky wrote:

I think perfection is too high a standard. It would require a very consistent cheek weld and a absolutely solid mount. That doesn't move at all to rule out movement of the scope.

If #5 occurs I would think it is operator error and not a scope issue.

For me #6 would not be an issue since I am not aiming at the edge of the FOV. The reticle isn't there. Even if I am using extreme Kentucky windage.

#7 I think you are referring to a FFP scope not a SFP scope. SFPs are only calibrated at one magnification setting.

With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.

That would be considered some sort of assault, anyway...  "scope abuse"... can't have that... you should never slap your scope under any circumstances...

Or your wife or girlfriend.

Unless they like it.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 15:54
koshkin View Drop Down
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Originally posted by dbooksta dbooksta wrote:

I've learned the hard way that it's important to run a battery of tests on scopes as soon as I receive them, and occasionally as time goes on.  But I'm not sure what the acceptance criteria should be for some of these:
  1. Return-to-zero: Dial elevation and windage to extremes, then back to their starting point.  If the reticle doesn't return to its initial point exactly, reject? If the scope is intended to be dialed, yes.  If the scope is intended for set-and-forget use and stays zeroed when you do not touch the turrets, not necessarily.
  2. Reticle cant: Align reticle with a straight edge and dial elevation.  If it deviates left or right from the edge the reticle is canted with respect to the adjustments.  Reject for any cant, no matter how small? In a set-and-forget type scope where you do not spin the turrets in regular use, I do not care much about reticle cant.  If turrets get worked all the time, any cant that I can detect by looking or shooting is not acceptable.
  3. Click calibration: While sighting on a calibration target (i.e., verified marks at verified distance), dial elevation and windage.  Typically we have 1/4MOA or 1/10mil clicks.  How much deviation from the indicated value should be allowed before rejecting? No simple answer to this one.  Once again it depends on how the scope is used.  Generally, if the reticle matches the turrets, I do not care (i.e. if both are off by the same amount).  If the scope comes with covered turrets, I do not care about this.  Generally, if you are using a calibration target make sure you are doing it right.  These days everyone is trying to do it and once the errors get compounded, a lot of in-spec scopes get sent to the manufacturer. 
  4. Click consistency: If the reticle adjustment effected by a click varies at all across the adjustment range, reject?  See the comment above.  It applies.
  5. Parallax (if the scope has a parallax adjustment): Dial parallax to bring a target within focus, then move the eye off-axis.  If the reticle moves at all with respect to the target, reject?  Dial the parallax turret to get rid of parallax.  If it does not work, reject.
  6. Focus: If a flat target oriented perpendicularly to the scope cannot be kept in focus across the full field of view, reject?  This is not the test you can easily do on your own.  
  7. Reticle accuracy: If the reticle marks do not perfectly correspond to the specified angles, reject?  (For SFP reticles, this would be a reject only if they do not correspond at any magnification that can be dialed.)  That depends on the price. 
  8. Recoil resistance: Assuming the scope is securely mounted: Dial the reticle, check its center, then slap the scope (without moving whatever it's mounted to at all).  If the reticle moves at all, reject?  Not necessarily. Almost all old Leupolds needed this settling, but once settled POI no lnger moved.
I assume that absolute perfection in the above measures can be expected from top-of-the-line scopes (i.e., $2k+).  But I suspect that not allowing any errors in these tests with many scopes would be unrealistic.  (I.e., one could test every scope coming off a production line and not find a single one that satisfies, or can be repaired to satisfy, all of these.)  So how much allowance should be granted and at what levels?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2017 at 16:57
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My thoughts of what applies to these has very much to do with price level.  I would not expect at all the same level of performance for a $300 scope that I would expect from a $3000 scope.

Are these tests conducted by shooting a rifle with the scope mounted, or with the scope mounted in special stand for test purposes?  I don't know any shooters that can shoot exactly to point of aim every time.  Even if the shooter was capable, the rifle & ammo may only be able to produce 1/4" to 1/2" MOA results.  Some variance will occur even with an expensive rifle/scope combination and excellent shooter.

Parallax and focus are not interchangeable.  Parallax may be correct, and focus not be perfect in even expensive scopes.  I have one that will be sent back to the manufacturer this winter to be checked.  When parallax is set, focus is sometimes quite off.  The further the distance, the more out of focus.

What is acceptable to me depends on price, and how it will be used.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/31/2017 at 20:18
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Originally posted by cheaptrick cheaptrick wrote:

I consider it defective when it say's...Barska on the box. Big Grin 

Barska made the best set of $7 binocs I've ever owned.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/01/2017 at 04:48
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Originally posted by Alan Robertson Alan Robertson wrote:

Originally posted by cheaptrick cheaptrick wrote:

I consider it defective when it say's...Barska on the box. Big Grin 

Barska made the best set of $7 binocs I've ever owned.


😂👍🥃
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/30/2017 at 11:53
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Seems to be a very relative set of guidelines. If you are a serious 1K shooter then all apply. If you are destroying coke cans in a gravel pit, theres a lot of leeway. That said even for 7$ we still would expect functionality. I did get a scope in a rifle combination and its function is to hold a freezer lid propped open, which it does well.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: October/31/2017 at 11:11
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Originally posted by rogn rogn wrote:

I did get a scope in a rifle combination and its function is to hold a freezer lid propped open, which it does well.

It was nice to get a chuckle in today.....thx
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/15/2017 at 13:41
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Originally posted by Sparky Sparky wrote:


With #8 I am not sure you could duplicate the recoil impulse by slapping the scope.

Here's another way: 30 rounds of .338 Lapua Magnum.  Both scopes start dialed to the same point of aim.  At the end, if they're still centered on the same point, I feel more confident in their recoil resistance!

MRAD .338LM with two scopes
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/15/2017 at 16:59
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That's a good test, but if you really feel adventurous, remove the muzzle brake and repeat it.

ILya
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