Is my scope Broke ?

Get or give advice on equipment, reloading and other technical issues.

Moderator: Mod

Message
Author
Tim L
Posts: 876
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: Is my scope Broke ?

#31 Postby Tim L » Sat May 11, 2019 9:05 pm

wsftr wrote:I always find scope testing so weird...I never take my scope and bang it on something or throw it down the field, I stick it on my rifle and shoot it...why don't they test them that way....the vibrations going through the scope will be very different.
Everything I've read and experienced so far...my money is on the scope.
I use NF exclusively.


I'm working with Peter Smith to make a collomator to test scopes. (OK he's telling me what to do. He's made a couple before.)
The issue with applying "the torture test" is ensuring you can put the scope "exactly" where it was before the test to see if anything has moved. If you can come up with a design that can complete the test you want I'd be keen to hear about it.

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Is my scope Broke ?

#32 Postby pjifl » Mon May 13, 2019 12:58 am

Dynamic testing of a Riflescope by applying sideways impacts is not as silly as it sounds. The reason is that small back and forth movements of lenses and components have almost no effect on Point Of Aim which is usually caused by sideways movements of lenses or sections of the Zoom mechanism. In any case, a testing system to test on the rifle between shots is extremely hard to set up and introduces a lot of uncertainty within itself and its attachment to the rifle. If light and small, its magnification will be limited so it will be nothing like as precise in use as a larger heavier separate Collimator. The optical components also need to be designed for the job and exquisitely accurate while a larger Collimator can use off the shelf more commonly available and affordable components. I know of no scope manufacturer who has designed and built a device for use on the rifle which could be guaranteed to the precision we demand. I think it could possibly be done but it would be very awkward to use. Anyway, for a manufacturer, the main advantage of systems in use are that testing can be done in a controlled environment inside a laboratory. They can also test a lot of other important parameters and are part of various necessary adjustments during manufacture.

Peter Smith.

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Is my scope Broke ?

#33 Postby Gyro » Mon May 13, 2019 6:35 am

The prahblem with this discussion folks is it might carry the implication that perhaps we all need to test our scope ? I can't be bothered, but then I've paid good money for a supposedly top scope and when my boolits don't go where I want them to then I'm suspecting other causes. And those "other causes" are endless.

It's not anything subjective after all ; either the scope is adjusting reliably or it aint ? Either the scope has backlash or it doesn't ? Are the internal springs getting tired ? Are their any plastic parts inside and if so will the plastic wear more and develop clearances that another scope with more durable materials won't develop ?

Lots of 'simple' mechanical questions.

Where's a scope designer/engineer when we need one here in this discussion ?

wsftr
Posts: 202
Joined: Tue Jan 30, 2018 12:58 pm

Re: Is my scope Broke ?

#34 Postby wsftr » Mon May 13, 2019 8:47 pm

typical testing of very expensive scopes (from what I've seen over time anyways)

https://youtu.be/gMNg0q7IMB0

What really happens to a scope when you use it as its intended

https://www.youtube.com/watch?v=s5pVya7eask

a little tongue in cheek there. ;)

I've personally had a leupold go bust. At 100 yards with a very accurate 6mm I couldn't get it to keep the same POI from one day to the next. It came back with a fully rebuilt tag.
I first hand know of three NF go bust, two in the middle of Nats (many years apart) and one in club days. One of the scopes the elevation mechanism went...so the repair tag said.

Scope problems are/can be very difficult to track down...you have to have a lot of confidence in your other gear to put the finger on the scope. generally it looks like trying everything but the scope and then sending the scope away out of desperation and the fault goes away.

IMO despite the scopes being very expensive the "easy" option of testing are used. I guess I would hate to think how expensive they might be otherwise.

I do agree that side impact testing is useful. However that is only a part of the usage. Rifles have a unique recoil and torque pattern. Most testing I have seen is monolithic in that there is a vertical or sideways whack and definitely not when a recoil pulse/vibrations are being transmitted down.

The most relevant testing I have seen so far is a known frozen scope locked into place along side the scope to be tested and shots fired.

I really like my NFs - got rid of everything else...doing some research though...the Kahles are coming through the side by side shot testing very very well....mmm...

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Is my scope Broke ?

#35 Postby pjifl » Mon May 13, 2019 10:04 pm

Notice that the repeated accelerations are sideways (vertical mainly) in that video. The rearward acceleration will cause stress and possible wear, but if any component inside the scope moves laterally it has no effect on POA. Impacts on a Riflescope in all directions can be applied in the laboratory fairly easily.

Twin scope testing mounted on a rifle sounds simple but there are problems.

1/ Are all the lenses 'frozen' The focus mechanism is not, nor is the graticule itself. Are the entire x and y knob adjustment system all totally frozen ? Usually it is simply he zoom mechanism.

2/ A good collimator will give a much clearer image and allow smaller measurements.

3/ You now have two sets of mounts to introduce errors. Mounts are a real weak point and often are the source of small POA change.

Also, remember that there are many other faults that can be present within a Riflescope. Some of these can be measured quite routinely with a collimator. Like, can you guarantee that tracking is truly vertical as defined by your Graticule ??

BTW, the Nightforce testing video is a bit misleading. It was obviously done as a quick demo more than showing real care with the measurements which were very hurried. Notice that the tester kept his fingers on the Riflescope when it was replaced repeatedly in its mounts. I can assure you that even this contact will result in slight bending of the Riflescope which is easily detected in a good quality collimator. It is also instructive to calculate exactly how smooth the scope tube needs to be or how easily some dust or grit will change contact. Or even an oil film. Or how much the scope tube is distorted from circular during clamping. We are down to microns ! Many Optical instruments where a component must be replaced in a guaranteed position use precision Spherical Sapphire or Silicon Nitride contact balls.

I am the first to admit that testing a riflescope for all problems - especially intermittent ones - is extremely hard and problematic - and any extra testing may be useful.

Behind all of this is the fact that most 'broken' Riflescopes returned to the manufacturer simply have nothing wrong with them. Of course some are defective or wear and that is true of all makes. I suspect the top scope makers often replace parts as a matter of course for peace of mind both for the shooter and their own good name.

BTW, there is a lot of 'plastic' used in top riflescopes in small critical parts. Plastic conjures up 'cheap and nasty' but there are unique plastics and elastomers and glues that all contribute to smooth precise operation. A study of patents shows how much they contribute to better lens anchoring and precision sliding parts. Especially with respect to keeping prices moderate.

Peter Smith.

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Is my scope Broke ?

#36 Postby pjifl » Tue May 14, 2019 6:34 pm

Rich,

I think I sent a message to you !!!

I find the messaging very awkward. Let me know here if it does not come through.

Peter Smith.


Return to “Equipment & Technical”

Who is online

Users browsing this forum: No registered users and 31 guests