Focusing Australian Optical Co. Model 1918 Scope?

[RobD]

Does anyone know how one adjusts the focus on the Australian Optical Co. Ltd. Model 1918 (3x) Scope?

Information

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[Valleysniper]

See pic here of Brit Model 18:



See the straight knurled focus slider at 6 O'Clock halfway along length of scope, slacken off the central screw slightly, but do not remove and move slider forwards and backwards to achieve focus. Tighten screw again when finished.

[Son]

SpikeDD, you may be entering into a problem zone here. To focus the scope you need to loosen the screw in the collar that is centrally located on the bottom of the scope tube. The focus itself is adjusted by sliding the collar forward and back slightly, much the same as the adjustment on the side of an Aldis scope. The only trouble is, one of the "improvements" that AOC made in the design of the Patt18 scope was an improved waterproof seal. The slide may be difficult to move, so take great care.

Here's a couple of pics, one showing the stripped tube with the focusing slot exposed, and the other a complete scope showing the focusing slide underneath.

[Peter Laidler]

Ah, you've all missed the IMPORTANT point chaps............. What do you want to focus RobD? If it's the grat that needs focussing, then do exactly what you have been told above, but with a degree of care.

THEN mount the telescope onto something solid, aim it onto a distant aimimg point (a DAP in Artillery parlance) such as a telegraph pole of something similar. Then move your head and eye left and right across the ocular lens and effectively across the field of view. The tip of the grat MUST stay on the same point of the DAP at all times. If it doesn't, or appears to move to the left/right or up/down, you have parallax and you'll need to focus the telescope onto the IMAGE. (Because don't forget, you are actually looking at an image that's now out of optical focus)

Then it becomes a bit more complicated.....................

[jayhovers]

Need some help with adjusting the windage on a 1918 scope. My sun shade rotates nicely but I'm not sure how to remove it. Any help is appreciated.

[Son]

Need some help with adjusting the windage on a 1918 scope. My sun shade rotates nicely but I'm not sure how to remove it. Any help is appreciated.

Take a look at the Lithgow Sniper survey in the sticky posts above. I now have almost 10% 0f production recorded on my spreadsheets and offer to answer any questions I can for contributors of details. All owners details are kept private. If you would like to contribute I can email a short question sheet if you prefer.

anyway, to the job at hand...
Here's a cut and paste copy of a piece I did a while back..... as usual, any and all questions, comments and corrections welcome...

+++++++++++++++++++++++++++++++++

Adjustment of windage in an A.O.C. Pattern 1918 telescopic sight as fitted to the Lithgow No1 MkIII* HT sniper rifle.

NOTE: I have photographed this process with the scope on the rifle as it was the easiest place to work on it. Some of the description may sound like kindergarten stuff, but I don't know the skill levels of people who may use this, so I default to try to leave nothing to guesswork for the less experienced.

Firstly, you really have to be sure the scope needs adjusting. I wouldn't recommend anyone do this any more than absolutely neccessary. Firstly, take the scope off, wipe every mating surface of the mounts and bases, and re-install the scope. (I've seen one grain of sand cause 3" off at 100yds-The rifle shot spot on after cleaning)
Check it for movement in every direction, if it isn't locked in tight you are wasting time adjusting it.
After firing a couple of fouling shots, and using the same ammunition throughout, fire a five shot group at a clean target at 100yds. Take the scope off, clean all surfaces again, and fire another group on another target. If the two groups are similar sized and centred about the same distance from the aiming point, you are ready to adjust. If not, fire a third group and consider the results of it and the second group.
You may need to have somebody else shoot a couple of groups to be sure... perhaps the innaccuracy is the rifle, not the sight adjustment.....

The distance from point of aim the mean point of impact in inches is what you need to know. You will need a jewelers screwdriver, and a home made tool pictured below, to do the job.

The scope adjustment is done at the front lens. The lens shade unscrews from the collar on the scope body. You will need to hold the collar, the whole assembly can rotate on the scope.

Attachment 19708 Attachment 19709

(Please NOTE how fine the thread is and how delicate the parts are. Take great care not to drop any parts as the slightest ding will make them impossible to re-assemble)

You will see a tiny screw through the tube under the shade. There are three of these spaced equally around the scope to lock the components together. Loosen all three a turn or so, being carefull not to let them fall out.

Attachment 19709Attachment 19713

Looking from the front you will see there are two rings outside the lens. The outer one is fixed and has several graduations marked around the top half. The inner one has two slots directly opposed. Here, I would put a dot across the two with a texta so you can see where it started from. Take the scope tool and place it into the two slots in the inner ring. You should be able to rotate the inner ring a little (one graduation and back will do) just to confirm it isn't seized DO NOT FORCE IT.

Attachment 19710

The adjustment is five inches at 100yds per graduation. Yes, half a notch will give you 2 1/2 inches. If needed, measure one increment with calipers and divide it by five to give a measurement of movement for one inch.
Here's the killer... I can't remember which way is which. If you bore sight the rifle to a target, then move the adjustment one increment one way, you should be able to pick which way it went. Return it to where it was, then do the measured adjustment from the original starting point. Write down exactly which way you went and how much. If you need to reverse the process it will be easier if you know what you did.

Attachment 19712

After adjustment is completed, gently nip up the three lockscrews and carefully re-fit the sunshade.

The tool I made from a piece of 1mm stainless steel shim. I coloured the end so you could see the shape, but it doesn't need to have a stepped part, it can be flat across the end. Be sure to de-burr the tool as it may be harder than the scope and mark it. Take care not to let it touch the lens.

Attachment 19711

[Craig Eberhardt]

Ah, you've all missed the IMPORTANT point chaps............. What do you want to focus RobD? If it's the grat that needs focussing, then do exactly what you have been told above, but with a degree of care.

THEN mount the telescope onto something solid, aim it onto a distant aimimg point (a DAP in Artillery parlance) such as a telegraph pole of something similar. Then move your head and eye left and right across the ocular lens and effectively across the field of view. The tip of the grat MUST stay on the same point of the DAP at all times. If it doesn't, or appears to move to the left/right or up/down, you have parallax and you'll need to focus the telescope onto the IMAGE. (Because don't forget, you are actually looking at an image that's now out of optical focus)

Then it becomes a bit more complicated.....................

Hello there,

My pattern 1918 scope is just a little out of focus. How do you suggest I go about focussing it and how will I deal with with any parallax issues? I don't want to touch it if this is going to be difficult. What range should it be focused at?

[RobD]

Badger, Son: could this be made into a "sticky"?
Son, perhaps you could also show with photos how to focus the scope and how to adjust the vertical scale on the drum (if that were possible).

[Badger]

Badger, Son: could this be made into a "sticky"?
Son, perhaps you could also show with photos how to focus the scope and how to adjust the vertical scale on the drum (if that were possible).

We have way too many "stickies" now and it's the kind of content that begs to be put into the form of a written article for the MKL ...

If someone would do that, we'd be happy to publish it for the benefit of everyone ....

Regards,
Doug

[Son]

We have way too many "stickies" now and it's the kind of content that begs to be put into the form of a written article for the MKL ...

If someone would do that, we'd be happy to publish it for the benefit of everyone ....

Regards,
Doug

Leave it with me... I'll add the focusing info including Peter's input above for for everyone to check/ proof read before it's MKL'd (if that's ok...)

Brad.