TargetTalk

I am totally new to rifle. I notice that for a modern match rifle, the front sight have two lenses. Maybe one is for a lens, the other is for a filter. But it seems to me that all the filter act as a lens anyway. I presume you pick both the front and back lenses of the same diameter.

However, is it OK to put in two lenses of different diameters into the front sight? In this case, for example, front is 2.8, back is 4.4 filtered. My thoughts is that the larger diameter one will help me to aim the target itself, or at least as close to the 1 ring as possible, while the smaller diameter is for aiming the bull, or as close to bulls-eye as possible. It seems to me that with two concentric circles of different diameters, it is easier to aim, compare with two concentric circles of one single diameter.

I am not asking for "personal preference". I am asking if this idea is correct or incorrect, a yes or a no, a good idea or a bad idea, one that creates good habit, one that creates bad, etc.

I use the search function and nothing comes up. Hence posting here and ask for some advice.

Under ISSF rules you are only allowed "Plain Filters" including polarisers fitted in the rifle sights, both front and rear. The threads in the front globe allow for fitting both an element, of whatever shape you like, and a palin/polarising filter. There would be no percivable advantage to using more then one element. In the sight picture you can only see the aiming mark not the 1 or 10 rings. Of course under the domestic rules of many NGB's lenses are allowed either in the front or rear sight, but not both. Some even allow the use of a lens in both front and rear sight, and glasses, but by then you are approaching having a simple Galilean telescope.

Alan

Conradin,

I was a little confused when I first read your question, and I think others may be as well.

What you are describing is called a foresight element, not a foresight lens.

A foresight lens is just that, a lens; the lens is clear (I'm sure you get one that is tinted, but I haven't seen any), and makes the target look a little larger, which can be easier for older eyes to see. Foresight lenses are permitted in NSRA (subject to certain caveats), and I believe US-NRA matches, but not in ISSF matches.

A foresight element is a metal ring, or perspex disc with a chamfered hole. These are used to aim the rifle, and do not magnify the target. Perspex elements are sometimes tinted, but that's all.

Now to answer your question. No you do not want to use two elements together. The difference in the diameter of the aperture is so small that you won't see two separate rings, just one slightly thicker ring, with an inner aperture that's a bit too small. Even if you could have two distinct foresight rings, this would be very difficult to aim. Aperture sights work by area aiming (common in pistol shooting I believe). You focus on the foresight, (and ONLY on the foresight), and centre the target. It's then just a matter of adjusting the rearsight to centre your shots.

That said, there is a product which sort of resembles your idea. This is the Centra Duplex. It's an attachment for the rearsight, that places a second ring inside the rearsight aperture, but around the foresight. The duplex isn't there for aiming on the target, but to make it harder to unknowingly misalign the foresight in the rear aperture.

Tim S wrote: What you are describing is called a foresight element, not a foresight lens.

A foresight element is a metal ring, or perspex disc with a chamfer hole. These are used to aim the rifle, and do not magnify the target. Perspex elements are sometimes tinted, but that's all.

Yes! The rifle came with 7 sets of foresight elements, each set has elements from 2.4 to 5.1. They are very old, from the seller. All of them have a hole, whether it is clear, or filtered (in light red). The hole itself, when aiming, act like a clear circle. You cannot tell whether the hole is chamfer or not with the smaller diameter ones, but for the 4.4 and the 5.1 you clearly can tell it is chamfer because it is inward conical. The edge of the hole is the circle at which I use to aim the target.

The question really arises from what if I put one element of 2.6 and another one with 4.0 to create two circles. It seems that the answer, from you, is a no; that the two slots from the front sight were meant for a normal element and a filter. So I should choose, 2.6 clear element for the front, and a 2.6 filter (light red) element for the back, despite the fact that both have chamfered holes and could be seen as circles for aiming.

I hope that was what you mean.

That said, there is a product which sort of resembles your idea. This is the Centra Duplex. It;s an attachment for the rearsight, that places a second ring inside the rearsight aperture, but around the foresight. The duplex isn't there for aiming on the target, but to make it harder to misalign the foresight in the rear aperture.

The long arm that I have is incapable of doing that, it is just a generic basic diopter. Is what you describe here, legal?

Thank you for clearing some terms for me. A match rifle has so many more terms than a regular rifle that I am still learning how to identify and name them.

conradin wrote:
The question really arises from what if I put one element of 2.6 and another one with 4.0 to create two circles. It seems that the answer, from you, is a no; that the two slots from the front sight were meant for a normal element and a filter. So I should choose, 2.6 clear element for the front, and a 2.6 filter (light red) element for the back, despite the fact that both have chamfered holes and could be seen as circles for aiming.

You will only want to use one of the elements (apertures) in your foresight. Out of curiosity, what is the brand (manufacture) of the sights? I am unable to picture the multiple areas where the elements can be placed.

John

Ok,

now we are talking about the same thing.

Almost all plastic or perspex elements will have a chamfer. The chamfer creates the ring by refracting light, so the chamfer looks black; no chamfer = no ring. The chamfer will be there on the smaller apertures, but if the element is thin, the chamfer will not be noticeable. The exception is where a plastic element has a metal or black pastic insert to make the ring.

Again, if you put a 4.0 and a 2.6 element together, you will see a 2.6 aperture with an extra thick ring around it. I don't think the elements will be far enough apart to create the effect you want, so the gap between them will be very small and more of a hinderance than a help.

Also the 2.6mm element is really a bit too small. You want to use an aperture that is large enough to contain the target, i.e. no matter how much the gun wobbles during aim, the foresight does not overlap the target. For standing AR most people seem to use a larger element (4.0+), as you hold is naturally more wobbly. 2.6mm would be much too small, so it will overlap the target; even in prone, where the gun is much steadier, a 3.2mm element is considered about minimum.

Your foresight, like all others, was designed to take a single element. Some have the front of the tunnel threaded to allow screw-in colour filters, polarisers, or spirit levels to be used. Spirit levels are not legal for AR, but tunnels are often used for both AR and smallbore, where these are legal.

Yes the Centra Duplex is ISSF legal, it contains no lenses, only extra aiming reference (and colour filters or a polariser if desired). Several prone shooters used them in last year's Olympic final. The device screws into the front of the rearsight; most are threaded here to accept anti-glare tubes (small sunshades).

Conradin,

Just to dispel any lingering doubts I had that two elements would not work, I tested this earlier today.

I started with a 4.1 in front of my normal 4.8, and as expected, I saw a 4.1 with a thicker ring. To make the test fair I then tried a smaller element, to increase the difference, in fact my smallest a 3.4mm. The result was still the same.

The answer to aiming is just to practise, and make your hold steadier.

corning wrote:
You will only want to use one of the elements (apertures) in your foresight. Out of curiosity, what is the brand (manufacture) of the sights? I am unable to picture the multiple areas where the elements can be placed.

John

FWB.

Thank you. I did not know that the ring is to contain, as opposed to match the target or bull itself. No wonder it is so hard to aim, as I cannot hold the long arm steady enough to totally match the circle with the bull.

I am using 2.8 right now. I will heed both of your advices and change the two elements (regular and filter) to 4.0.

PS. Just to make sure, 4.0 for 10m right? Even 2.8 seems to be larger than the bull.

4.0 is about the minimum for 10M rifle shooting. 4.2 to 4.4 has been the norm for our young shooters (and old eyes often need more light). Many use larger, and some are having great success with very large (7.0) apertures.

I use a 4.8 front aperture for 10m and I prefer to use upward of a 5.0 aperture for 50' or 50m.

Hi Conradin,

there is no one real size for the front sight insert for all of us because we all see different. Our seeing is always also a kind of our perception or cognition. And it depends also from the sharpness of our vision. It depends also from the contrast of the target. But there are some rules of thump for choosing the right foresight element. The distance between the insert and the bull seen from the shooter should approximately have 1/3 to 2/3 ratio. Better shooters may choose here a slightly smaller insert, but never to small. And also the distance between the front sight tunnel and the rear sight iris should be the same ratio. This depends also from the distance of the shooters eye from the rear sight iris. And here comes the bigger 22mm fore sight tunnel discussed in an other thread here to play. Many shooters prefer a real close distance to the rear sight iris and then a bigger front sight tunnel can avoid aiming errors. Tim S. mentioned the new Duplex system. This is for the same reason to avoid aiming errors not to center the front sight insert and tunnel perfect in the rear sight iris.

For choosing your best insert diameter you have to test which diameter will give you the best possibility to predicting the position of your shoots on the target. This is not necessary the the target with your smallest group.

But general, it is not true, that a smaller front sight insert give you always better results. As i said it depends much from the sharpness of your vision and jet much more from your skills to hold the rifle. If you are more a beginner and your hold has still much moving then a bigger front sight insert can give you better results. The most trouble at this stage doesn't come from wrong aiming. Learning pulling the trigger right will bring you much more progress and with a smaller insert you will see much more of your movement and wobbling and this makes pulling the trigger right always harder.

If it comes to the inserts there are many different styles. The oldest inserts are made of metal. Not bad, but they give you often a slightly fussy rand between their black and the white of the target. Inserts from plastic or glass won't do that. You can use inserts with one fixed diameter or you can buy a foresight iris. So you can change the diameter of the insert easier. Some of this irises or some tunnels are also rotatable. So you can easier control your canting error. Canting the rifle may a good option for a better head position, but you have to control this canting angle.

But maybe this is an other lesson on the way to a good rifle shooter. The first point for good match shooting in the standing position is the position. And then it comes to the NPA, the natural point of aiming. Good trigger skills are also important, as i mentioned. On the other sight and against often heard belief outstanding good seeing isn't the most important thing for a beginning match shooter. Most of the errors are not the result of aiming errors.


Regards

Frank

conradin wrote: Just to make sure, 4.0 for 10m right? Even 2.8 seems to be larger than the bull.

There will always be a fine ring of light around the inner edge of the aperture, even if the aperture is smaller than the perceived size of the target.

For instance the 50m rifle target appears around 2mm at standard barrel length. Even with a 2.0 or 1.8mm aperture you will still see light, even though the aperture is operlapping the target most/all of the time.

This is because light is refracted off the inner edge of the aperture; this happens becuase light enters the foresight tunnel from all sorts of angles, not just parallel to your sight line. This means the inner edge of the aperture is slightly fuzzy, and there is a halo of "dirty" light around it. The halo is there all the time, but can be mistaken for the target paper if the aperture is too small (so the gap between the ring and target is very fine).

A larger element puts this halo further away from the target, giving a better sight picture, and also prevents accidental aiming error.

Tim

For a new shooter I would recommend starting at around 4.5 mm given you are using a rifle without sight extensions. If you place the ring over the aiming mark so that it cuts it in half, you will still see the white along the edge as Tim mentioned. In aiming the rifle you are still using an area aim, just like you are with a pistol, you need to have a large enough ring that when normally on aim the aiming mark stays completely within the foresight ring. As you gain experience and your hold improves then you can start to reduce the foresight ring diameter. One of the training exercises we do at our club, and is often done as part of the "warm up" when shooting on club nights is to shoot using a plain black card. If your setup/position is correct, then this exercise will show you your NPA, and it is normal that all shots will fall within the aiming mark if that is substituted. The reasonable shooters will actually normally be able to hold around the 7-8 ring during this exercise. If the shots do not form a group, then you need to work on your hold, and if the group is not centered on where the center of your aiming mark would otherwise be then your NPA is off and you need to adjust your position until your NPA is correct. This is also something that using something like the SCATT training system can come in useful, if you know how to read the traces correctly.

Alan

I forgot to mention that the filters are M18. So when you mention 4.6 for example, I presume it is M22. What is the equivalent I should use for M18?

Does the aperture of an M18 needs to be larger than a normal M22 to produce the same effect?

The diameter of the foresight element, it's not a filter, is really dependant on the sight base rather than the diameter of the globe. If you are using a rifle with the "standard" sight base you would use pretty much the same size element be it with an 18 or 22 mm globe. At the club we have club rifles with 18 mm globes (Walther) and also 22mm (FWB), they all run pretty much the same sight base and they all I think have around 4.5 mm elements fitted. These are rifles for the use of newcomers. Some of the more experienced shooters are using sizes down to 4.1 mm but that is very small really for the standing position, and not as size you would want to be using until you are capable of shooting over 550 (or 370 in the women's match). The odd thing is that the set of elements that comes with the latest Walther LG 400 match rifle for example are actually much more suited to prone shooting, and even then are on the small size. Just because a set of elements is supplied by the manufacturer with the sights supplied with the rifle doesn't mean that they are actually fit for the use that will be made of them.

Alan

No one has come out and pointed out that English and American are not the same language.

Front Sight = Foresight
Aperture (or iris) = Element
Soccer = Football
Pop Tart = The kind of girl you would not bring home to meet your mother
And so on

So in the US we typically refer to apertures for the openings you look through, I have also heard them referred to as peeps in the rear sight, iris, or globes.

M18 vs M22 is the outside diameter to fit different styles of sights. There is also an M30 size out there, but that is typically more for long range. Champion Shooters Supply sells all ID/OD Color combinations possible.

http://www.championshooters.com/index.p ... Itemid=111

Typically, a human eye can resolve actual images down to about 1 MOA, so your ability to resolve just by looking at the 'circle in circle' image cannot typically tell if you are in the X or the 10 ring, just from image analysis.

However your eye can also discern about 16 shades of brightness, so if your bull is a little off center, the width of the white ring between the bull and your aperture will be a little wider = brighter on one side, and narrower/dimmer on the other. Using those brightness cues, you can center a target better than just what the image allows. So you want the aperture to be sufficiently bigger that the perceived white band appears to be a brightness that falls midrange in your eye's brightness sensitivity. All eyes are obviously different, but the general consensus for outdoor shooting is an aperture about 2x the bull diameter, so for a 6MOA bull, you want a 12MOA aperture. Top shooters typically use adjustable apertures, so if the brightness goes up/down, they can manage the intensity of the white ring by increasing/decreasing the aperture size slightly.

What you can do, and I sell these for the larger 30mm sights, is to put a smaller aperture in one end of the front sight, and a larger color aperture in the other end. This allows you to use the smaller aperture to aim, and the larger aperture only serves as a color filter for the area outside the aiming circle. This reduces the brightness of the light coming in from the perimeter area, and it allows you to swap out filters or remove them without having to touch the aperture that you are using to aim. Once you have a zero established, and especially after you have started a match, you do not want to remove/replace your aiming aperture, as you might lose your zero.

Art