Misc airgun open sight article

The intention of open sights (or ‘irons’ as they’re often termed), is to allow you to align the target with your eye via a sight element towards the rear of the rifle and another at the end of the barrel. These line up the bore of the rifle with the target, ensuring that you are sighting as close to the path of the fired projectile (pellet, bullet or shell) as possible – only if the sights are set up correctly that is!

BASIC AND PRACTICAL

The benefits of open sights include quick target acquisition, because you have a very wide field of view and as they don’t magnify the target, rangefinding isn’t ‘confused’ by an image-enlarging optic. Posh speak for a variable power scope! There are still quite a few models of good quality air rifles – mostly spring-powered that are fitted with open sights. These either consist of a post, bead or blade positioned at the front end of the barrel (fore sight), which is lined up in a U or V-shaped notch in the rear sight assembly.

A typical rear sight unit is usually fitted onto the breech end of the barrel, the action body or sometimes clamped onto the dovetails cut into the air cylinder for scope fitting – one example of this is the unit fitted to the Weihrauch HW77. Talking of which, most open sight Weihrauch’s also come with a selection of interchangeable foresight elements that fit inside the ‘hooded’ front assembly. Also, they have a rear sight that gives you four choices of ‘notch’ to line your preferred foresight element into. This might consists of V and U-notches with the latter offering curved or flat bases or even different widths. This is made possible due to the adjustable ‘square shape’ back plate the notches are cut into can rotate to show the sight-notch you prefer.

All good quality rearsights are adjustable for height (elevation) and windage (from side to side), so they can be set for the range required. Adjustments are catered for either by a set of thumbwheels - often numbered – but more basic ones found on older models of air rifles can simply be just a simple screw and plate.

BRIGHT EYES

Now becoming more commonplace on reasonably priced springers are fibre optic enhanced open sights or as they’re often referred to - ‘Tru-Glo.’ These offer a contrasting colour foresight (often a ‘red bar’ held on top of the post seen from the rear as a ‘dot’) that is lined up in the rearsight notch in the traditional manner. As the rearsight notch has fibre optic bars (usually green) set-either side. Many feel they help with faster target acquisition which to some extent they do. If you are thinking of purchasing a rifle with these sights fitted, look to the rifles that have hooded foresight blades because one accidental knock and the fibre optic bar will more than likely ‘shatter.’ Personally I’d say stick with those made of metal or toughened ABS.

ZERO HOUR

Zero is the term used for a pre-set point (distance) to which the sights have been adjusted so the pellet strikes the target to coincide with the centre of the scope’s crosshairs – or, in relation to an open sight set-up, the point where eye, sights and ‘strike point’ on the target all line up.

As a matter of interest, it surprises me how many airgun hunters don’t consider using a ‘red dot’ sight on a PCP air rifle because for close range shooting they give many of the same benefits as ‘opens.’ Plus they can be used with both eyes open and you only have two areas of focus dot and target as opposed to three rear sight, front sight and aim point.

I’ve mentioned on several occasions in hunting articles of my liking for these when shooting at close range against rats and feral pigeon. But I digress as when using open sights on a recoiling air rifle, a maximum zero and hunting range of 15 yards is often the accepted and recommended norm. This can be extended to 18-20yds if the open sights are good enough and your ‘iron-clad’ shooting of a high enough standard.

Another bonus; because ‘irons’ are so ‘forgiving’ at close to medium ranges, generally you can zero your sights at 12 yards and providing you don’t exceed 20, literally aim ‘bang-on’ for all quarry that presents.

ZERO

Setting zero with open sights is simple. Line the front into the centre of the notch of the rear; place it over the target with the top of the foresight element (blade, post or bead) level with the top of the rear sight. The object of accurate shooting is of course to produce what are known as good groupings. A group or string of shots - usually five – is fired into a paper target and the grouping is determined by the distance measured between the impact points of the most widely separated pellets in the pattern.

If this measured distance is 1 ½”, then you have a 1 ½” group. These measurements are now taken from the outer edge of the pellet holes (because they are easier to measure) and really should be termed ‘edge-to-edge.’ But if you read gun tests you’ll notice almost without exception reviewers such as I use the term C to C denoting centre to centre –

a competition term for the measurement taken from the centre of the pellet holes. For hunting purposes as long as you are consistent in getting good, tight ‘kill-shot’ size groups – you’re on target.

GETTING IT ON

Once you have your group it will be in a position relative to your point of aim and may need adjusting to bring it spot on. Most modern open sights are adjusted for windage and elevation on the rear unit only, as the front blade/post is normally fixed. Generally adjustment is by thumbwheels, which are marked as to direction. For example if the initial group; is left then the windage wheel will be wound to the right to bring it across. By the same token if the group is low then the elevation wheel is wound upwards, which will raise the U-notch causing you to lift up the muzzle to realign the sights. You might encounter slot headed adjusters that requires a screwdriver to move. The principle is identical though they are becoming rarer these days.

On that point you might also encounter older designs that have an adjustable front sight. Most basic is windage with the blade/ post set in a transverse dovetail. Here the correction is in reverse; for example if the group is left then the sight is moved to the left, causing you to swing the muzzle right to realign the sights. Elevation is the same - group high raise the sight so you have to move the muzzle down to realign. Remember this for adjustment directions - rear sight out of the error, front sight into the error. Also make corrections in small movements as it’s too easy to over compensate, most adjuster wheels have positive click stops you can feel and hear.

SENSIBLE DISTANCES

The furthest you can comfortably put a 5-shot group of approximately 1” should be your maximum hunting distance - and that applies to all sighting systems. Paper Targets are cheap, but don’t forget to have a solid backstop behind. Very handy are the 1” diameter target stickers that are available from most gunshops as the size is already exact for your purpose. Also as they’re bright orange they do help you align the open sights properly which you’ll become more natural the more you practice.

When you’ve mastered grouping, why not try your ‘aim’ using fall-flat targets. My favoured practice targets after I’ve set zero are now the 25 and 15mm ‘kill-zone’ types manufactured by Nockover Targets. However, the latter are too demanding for open sight shooting.

As previously mentioned, the main problem you’ll encounter with open sights for air rifle hunting is that they may partly obscure the target at longer ranges. Whilst this makes open sights ideal for indoor shooting at rats and roosting feral pigeon, this range limitation immediately makes it apparent why a scope is such a necessary addition for the airgun hunter wanting to take precision shots at longer range.

If you want the best of both worlds, you can on many air rifles mount your scope in ‘See-thru’ mounts designed so you can see under the scope ‘through’ the mounts to use the open sights for quarry that might appear unexpectedly at very close range. These situations and the use of red dot sighting systems are subjects I intend to deal with in the future…