OPTICS

The rifle scope, spotting scope and binoculars are day-optics, which is to say the reticles are still visible from about 30 minutes before beginning of morning nautical twilight (BMNT) and up to 30 minutes after the end of evening nautical twilight (EENT).  To extend this capability to some degree into the night the rifle scope is also fitted with a red rheostat. 

The AI AWM and the US Optics SN3 T-PAL are capable of being used with night vision equipment.  However generation 2 and 3 equipment is prohibited for export from the USA to civilians. This eliminated considerations for a night rifle scope or image intensifier, additional mounts, associated batteries and possible stock extenders.

Reticles  
The choice of reticle depends largely upon the chosen scope and manufacturer.  For long range shooting that means a reticle in mils or MOA.  The key to the optics in this system is that reticles and adjustments are all in mil radians.  Horus Vision reticles are a grid system that extends the mil dot system that many practical reticles are based on.  The H37 reticle is designed to engage targets out to 2500m.  The main central cross is higher in the field of view to allow more grid to be used at increased magnifications. 

The most significant benefit of Horus Vision reticles is that, after practice, they provide a significant speed advantage.  Rather than making windage and elevation adjustments and placing the cross hairs on the target, most Horus Vision reticles are used by moving the correct position on the grid to the target.  Apart from zeroing the rifle scope, the turret knobs are not adjusted when shooting.  This further provides fast second-shot correction and rapid transitions to multiple targets.

Table of Optical Characteristics

Rifle Scope

Binoculars

Spotting Scope

Laser Range Finder

Manufacturer

US Optics

Steiner

Leupold

Newcon

Magnification

5-25x

10x

12-40x

7x

Objective mm

58

42

60

25

Reticle

Mils
Horus H37

Mils
SUMR

Mils
Horus H32

Cross hairs
or Rectangle

Purpose

Aiming

Target acquisition
Range estimation

Impact analysis
Range estimation
Target identification

Range finding

Advantage

Rapid aiming

Widest field of view

Highest magnification

Most accurate ranging

Stabilisation

Bipod and Monopod

Handheld or Tripod

Tripod

Handheld or Tripod

Dimensions mm

300 scope
150 shade

120 x 122 x 60

MILs  
The Horus Vision H37 and H32 reticles incorporate a range finder and targeting grid based on the US Marine Corps where a circle equals 6283 Mils where 1 Mil equals 10.0 cm at exactly 100 metres.  The Russian military also use Mils, but their formula is slightly different again.

The Horus Vision H37 and H32 reticles are used as a range finders allowing accurate measurement to 0.20 of a mil.  The vertical targeting grid is used to compensate for bullet drop and the horizontal targeting lines are used to compensate for wind, lead and second shot correction.

Rifle Scope 
The usual selection for an Accuracy International rifle is a Schmidt and Bender (SuB) rifle scope, such as a 5-25x50 with a P4 Fine reticle.  However, SuB scopes were not available with Horus Vision reticles.  Horus Vision has a range of rifle scopes, and the Falcon, which has a 30mm tube, is very suitable for long range shooting.  This system uses a US Optics SN3 T-PAL 5-25x58 rifle scope because it was available with a Horus Vision H37 reticle and had the option of a 34mm tube, making it compatible with the AI riflescope mount.  The SN3 is designed for a sloped mount of 20° whereas the AI mount has a slope of 18°.  This difference will be recalibrated as part of the zeroing process. 

US Optics has a wide range of rifle scopes and an advantage is that the scope features are customisable, with some scopes having an option for a Horus Vision reticle.  From the US Optics web site, choose a basic model, and then select the options for the various components e.g. clicks in mils or MOA – per turret.  Then US OPtics build that scope just for you. 

For my kit the US Optics SN-3 5-25x T-PAL rifle scope was configured with the options of; parallax control with T-PAL on the left side, power 5-25x, objective - 58mm, tube - 34mm, eyepiece - lo profile rapid focus, reticle - Horus H37-22T, reticle lighting - 11 position rheostat (red), knob elevation - EREK 1cm at 100m, knob windage - US#1 M40 style metric, screw on objective cover, sunshade - 58mm fixed, honeycomb polariser / Anti Reflection Device (ARD), and an eyepiece cover - butler creek flip up.  As all ranging will be done in mils, scope selections included turrets graduated in .0.1 mils.  However, once a scope with a Horus Vision reticle has been zeroed there is no longer any requirement to use the elevation or windage turrets.

The number of elevation clicks available in a rifle scope is very important because in long range shooting the zeroing-in range will still often be just 100m.  That means to get to a range of 1200m it could be some 127 clicks on this scope with 10 clicks per mil.  Firstly, the distance that can be aimed is limited by the number of clicks available in elevation.  Secondly, as some scopes will usually require a second turret turn it is possible to get lost and not remember if you are in the first or second turn.  There are several options to minimise these effects, and most of these larger scopes require sloped bases so that you can increase the maximum elevation.  Generally, the larger the tube the more clicks that can be made.  Further, reticles such as the H37 have the cross raised from centre so that maximum required elevation can be achieved.

Binoculars  
A good set of binoculars with a good reticle is essential for practical shooting.  Binoculars provide a larger range of vision than the rifle scope, and are more useful for locating targets.  Further, most competitions do not permit the use of laser range finders, so a pair of binoculars with a mil reticle provides an additional tool for range estimation. 

Steiner is regarded as premier binoculars and I have carried a set of Steiner 7x50 binoculars through forest, desert and jungle.  They are fantastically clear, sharp, and bright – but they don’t have a reticle.  The majority of Steiner binocular reticles only have marks per half or full mil, which to my mind is not accurate enough for long range estimation of small targets.  Steiner has two exceptions – the Steiner 10x42 R Tactical binocular, and the 10x50 R SUMR binocular.  Both have the Steiner Universal Mil Reticle (SUMR) which has increments down to .20 and .05 mils.  The 10x50 was tempting because of the additional brightness and rubber armouring, but the 10x42 was chosen because it is more compact.  Replace the rain guard with the plastic one and get a tripod adaptor.

The compass function in a binocular would be handy to indicate azimuth when writing range cards.  However, compasses are usually calibrated to different magnetic zones around the Earth.  Therefore buying internationally is often not an option because a North American zone compass will not be accurate in New Zealand.  The Steiner 15x80 R Commander compass binocular is not readily available in New Zealand, although lower magnification compass binoculars from Steiner are often available here. 

Spotting Scope  
The spotting scope is to provide both accurate range estimation and close observation, including target impact analysis.  With a 40x magnification .338 bullet holes are visible up to 200m, whereas with a 60x magnification bullet holes are visible at 400m – both save a lot of time walking to check targets at a rifle range.  Tthe higher magnifications also magnify any mirage effect, so in some circumstances the magnification will need to be minimised.

Horus Vision can prove a H32 reticle etched into a Leupold 12-40x60 Golden Ring High Definition (HD) spotting scope. 
This has a Folded Light Path (FLP) lens and mirror system to reduce length.  The spotting scope is waterproof, charged with nitrogen to reduce fogging, has a magnesium body to reduce weight and add strength.  It also comes with padded soft-side case and is equipped with a ¼-20 thread tripod adaptor.  The soft case is designed to remain on the spotting scope at all times and has Velcro flaps to allow easy access to the eyepiece, objective lens and tripod adaptor.  Generically known as the ‘Mark 4’ this spotting scope, albeit with a different reticle, is the official spotting scope of the US Army Semi-Automatic Sniper System (M110 SASS).

Separately, the Leupold Digiscoping Digital Camera Adaptor snaps into place over the eyepiece and is compatible with camera lens diameters of 28mm, 37mm, 43mm, 52mm and 58mm.  In this case the H32 reticle will be shown in any photographs.

If observation is the primary requirement the alternative would be a Swarovski STS-80 spotting scope with a 20-60x variable magnification eyepiece.  This does not have any reticle.  The STS has a straight turret for the eyepiece and there is an alternate ATS model with an angled turret. A digital camera adapter and high definition (HD) optics are also available. 

Anti-Reflection Devices  
During winter months New Zealand, being in the lower latitudes, has the sun low in the horizon.  When looking through optics, this can result in lens glare and ‘washed out’ images.  US Optics and Leupold both have sun shades and honeycomb Anti-Reflection Devices (ARD) that will reduce both glare and reflection off the objective lenses.  US Optics has a sunshade and a honeycomb ARD for their 58mm objective rifle scope tube diameter and Leupold has a honeycomb ARD, made by Tenebraex, for their 12-40x60 spotting scope.

The ARDs have a hexagonal honeycomb with gaps letting light through.  The primary advantage of ARDs over sunshades is that they are much shorter, and less prone to damage.  In both cases the amount of light entering the rifle / spotting scope is reduced, but not noticeably.  The ARDs screw on to the scopes but due to the methods of attachment and tube diameters, sunshades and ARDs are not usually interchangeable across manufacturers.

An alternative from Leupold is their Sunguard ARDs which are akin to camera filters.  They slip in behind the lens cover and work much like a pair of sunglasses.

Laser devices are common on a modern battlefield and not all lasers are eye safe.  To protect operators some objective lenses are coated with laser filters.  Steiner, for example, has several of their military binoculars available with a Laser Protection Filter (LPF).  A disadvantage of such coatings is that they are highly reflective.  So much so that they can easily be seen in low light conditions.  Consequently, it is common to use honeycomb ARDs to reduce reflection and being effectively a set of tubes, they also reduce ‘laser strike’ from angles not in a direct line with the scope.

Tripod   
A tripod is required to stabilize the spotting scope and LRF.  It is also a mount for the weather station when reading wind direction, using the vane.  For compatibility all equipment uses the ¼” by 20 threads per inch camera type mounting.  As the LRF has an electronic compass, the tripod must also be non-magnetic.

Vectronix has a range of non-magnetic tripods, and the SST3-3, mini-tripod and monopod in one, is designed to be used from the prone position and is only 46cm long when stowed.  It comes with a detachable interface plate with a ¼” thread, three hinged legs and a 15° tilting mechanism with clamps.  It has a vertical telescopic column for height adjustment and a non-magnetic detachable Cullmann pan / tilt head with lever.  It also has a hard-metal ground spike for the monopod.  With a minimum extended length of 36cm, it is high enough to see over many grasses and the maximum extended height of 72cm means it can also be used while sitting.