Written by the Bevel Brothers.

This article appeared first in Muzzle Blasts Magazine, July 2007. You can read this magazine as well as every Muzzle Blasts ever printed by becoming a member of the NMLRA Today.

Dear Bevel Brothers: ['ve noticed a myriad of different sight set-ups while attending the Alvin York and Pennsyl­vania State chunk shoots. l've also seen many different sighter targets. What, in your opinion, is the best sight configu­ration and sighter target combination and why?

Jerry Stuck

Newport, PA

Bevel Up: Most of our loyal readers don't know this, but T almost majored in philosophy back in college! So that makes me practically the perfect guy to answer this question, right?

Bevel Down: Lemme see, now ... I re­member that. You needed three more hours that semester and the psychedelic finger painting class was filled up. So you signed up for Philosophy IO I and then dropped it because the class started at 8 AM and that was always just when the fish started biting. That's about as close as you ever came to "ma­joring" in philosophy.

But true enough, this question is much more philosophical than it is tech­nical. It's sort of like trying to find the perfect chili recipe or the best ZZ Top recording. Everybody has something that they like or that more or less works for them (or seems to, anyway). So that's why we decided to explore this seem­ingly esoteric topic this month - some times what seems to work isn't nearly as good as what would really work if we just knew about it.

Bevel Up: So first off, for the benefit of our newer readers, let me explain just a couple of fundamentals about chunk shooting. The main difference between chunk and other games is that a chunk target isn't your standard old concen­tric-circle-bullseye target that practically everybody else shoots at. What a chunk shooter is trying to do is shoot as many of his shots into one tiny little group as he possibly can. Using fixed. nonadjust­able, open sights, the shooter aims at a "sighter" target. This target is a size and shape that suits the shooter. It doesn't matter where the group is landing on the sighter target. just so long as all the balls are going into one small spot on the paper. Once that group is established with two or three preliminary shots. the actual record target, in the form of a big X, is pinned underneath the sighter tar­get with the center of the X located right exactly where the next ball is expected to hit the target. The next shot is fired using exactly the same sight picture and hold as Lbe last one. so if everything is working right. that shot will go 1ight on top of the last one and cut a nice neat hole in the center of the X.

Got it?

Bevel Down: So the problem is to find a sighter target and sight combination that you can see well, that doesn't tend to change the point of impact with varia­tions in light conditions, and doesn't tend to give you any more eye strain than is absolutely necessary.

Over the years we've tried and re­jected all sorts of sighters and sights. We've tried sighters made out of round bull's eyes, inverted triangles. dia­monds, inverted block-shaped "U-' things, squares, rectangles, parallel ver­tical bars, half circles, and orange dots. Some sighters worked better than oth­ers. Some dido 't work at all.

Mostly the sights we've tried have been variations on the standard square post/square notch open sights. I once tried a square post with a V notch filed into the top of it for a triangle point to fit down into, but quickly discovered that it was too darned hard to see to be effective. We've also tried about every imaginable variation on the width and depth of both the front post and the rear notch.

Bevel Up: What we've pretty much boiled it down to now is a black square on a light colored (target paper) background with a little piece of orange paper about a quarter inch below the bottom edge of the square. The orange is sort of a "no­go" barrier - in use the front sight post is held on a 6 o'clock position under the square with just a little strip of white showi11g between the post and the bot­tom edge of the square. If any orange shows, you know your sight picture is low and you raise the front sight back up to cover the orange. If you have the or­ange covered. but can't see the white strip under the square, you know you are hold­ing too high.

The width of the square is cut so that when lined up with the font sight blade at 60 yards it just exactly matches the width of the blade. That way, all you have to do is keep the vertical planes of the sight post lined up on the same vertical planes of the square to control your windage. Tf the wind changes in the middle of the match (af­ter you have already posted the X, that is) you can still save the shot by hold­ing off slightly. You know how wide the square is, so you can divide it into pieces across your sight and know about how far you are holding off with a given sight picture. 

I like to use a front sight blade about 1/8" wide and a square notch rear sight that lets just a little daylight in on both sides of the blade. The square I use for the sighter ends up being about four inches wide to match the blade at 60 yards. People with better eyes than mine tend to use finer sights and smaller squares.

Bevel Down: The main disadvantage to this system is that even with the no-go dots and the vertical registration of the front blade and the sighter square, it still has a tendency to change your point of impact with changes in light conditions and changes in your visual acuity as eyestrain sets in and the sights and tar­get begin to blur.

As we've discussed in earlier col­lllnns, eyestrain and varying light con­ditions will cause you to gradually lose the ability to focus on your sights and target as well as you did at the begin­ning of the match. Nobody can really focus on three points at three differ­ent distances at once (rear sight, front sight, and target). so any sight pic­ture is always going to be a compro­mise that leaves one or two of those things out of focus and blurry. What you have to do is make it a consistent compromise in that you want to always leave the same thing blurry the same way from shot to shot. The best choice, most shooters agree, is to leave the target blurry and keep the sights in as sharp a focus as possible. That also means for most people that the front sight should remain the sharpest and any blurring of the sights should fall to the rear sight. Shifting back and forth between which of those three things you consistently keep in focus will usually produce two distinct groups some inches apart from each other. It's a problem that takes prac­tice and concentration to overcome, and is what I see as the chief drawback to using the square target/square sight combination.

To a somewhat lesser extent, varia­tions in light conditions will cause the same multiple grouping problem. What happens is that as the light fades, the eye has less light available to keep the pupil contracted. Thar reduces the shooters depth of field (the length or distance between the sights that can be kept in more or less simultaneous fo­cus) and tends to leave the rear sight more blurred than it would be in bright light. With a blurred rear sight, it will appear that the top of the front sight is seated properly in the notch, whereas in reality it is being lined up with the top edge of the blur instead of the top edge of the rear sight. The result is a higher shot impact. When the light comes back up bright, the rear sight will be in sharper focus and thus bring the front sight deeper into the notch for a lower point of impact. People shooting adjustable sights, like in benchrest or some offhand matches, can compensate for this effect by dialing up the elevation slightly when the light brightens ("light'.f up - sights up"), but with fixed sights that isn't pos­sible. You just have to know it is hap­pening and allow for it when you hang the X behind your sighter or hold off on the sighter.

Bevel Up: The two main schools of thought on this subject of sighters and sights run to either the traditional square sights and a six o'clock hold on a bulrs eye of choice, or to a combination of donut sighter targets with pinhead sights, which is the "other" sight com­bination being seen with regularity at chunk marches these days. The princi­pal proponent of these sights has been Paul Griffith.

I wish I could say that his pursuit of this donut sight combination has been pure folly, but I can' L. That's because he keeps beating me with it and winning matches when I don't. You've got to respect a guy for that, even if you'd rather see him stay home once in a while.

Paul Griffith: I guess that I can't argue with you that there's a whole load of different ideas when it comes to targets at a chunk match. I"ve been using a pin­head front sight with a U shaped notch in the rear for about the last seventeen years as best as I can recall. I hate to say that they are the best knowing that some set of square sights might pound me like a cheap steak at the next match. To use these things you make a tar­get starting with a background paper, maybe fifteen inches square - a black circle eight inches or so across with a round white center circle that the pin centers in. Most folks refer to this tar­get as a "donut" because that's what it looks like. The front sight then is a little round bead about the size of a pin head, which fits snugly (when looking thrnugh the sights, that is) down into a U-notch open rear sight. The round pin head only goes down so that it rests near the bot­tom of the U, and sits so that the hori­zontal plane of the top of the rear sight is half way up on the round head. What you end up with is a U-notch with a round ball sitting half way down in it, with the ball centered inside the do­nut ring of the sighter. The image you get if the donut is sized correctly is sort of a floating ball on a stick with a halo around it showing through the back sight.

The first time I crossed paths with these sights was at the old Don Linkhart range near Xenia about 1990. It took a few hours when I got back to the shop to mill out a pair and I've been fighting with them ever since. At that time my old running buddy Wilson and I would commonly spend Sunday afternoons through the winter shooting chunk out the back of the shop. As time went by it became obvious that there was more to learn in order to get the good out of the things. We found that on the most over­cast, snowy, dark days we did our best shooting. Tom suggested that we shrink down the center on a good day to the point that it looked as bad as it did on a bad day. The group came together and we knew we were on to something.

We found that what we were up against was diffraction around the bead. A physics professor at a nearby college told me about an experiment that they set up to demonstrate this situation. A sphere is suspended in the center of a dark room and a light is introduced from one end. The shadow on the opposite wall will not measure up to what it should be because the light is bending around the ball. He went on to say that it is pos­sible to end up with a single point of light on the wall in the center of the shadow as the diffracted light converges from all directions.

If this doesn't exist with the sights then what we are seeing is only the difference between the diameter of the pin and the white center. But if you get your center down lo where it just halos around the pin and place a black dot in the center of the white you will no longer be able to see the halo. It has to be the diffraction causing this.

So in order to get any accuracy you have got to get the white center down to where you are basically seeing only the diffraction. If the center is bigger, as soon as you get the pin in the white anywhere it looks good even though you are not centered in it. This creates a problem as a larger target looks bet­ter and everything in your bead says that it should be better. Helping people set up their target [ used to say that they needed to shrink the target down as far as possible. These days 1 say start too small and work your way up an eighth-inch at a time until you can just see it and then quit. Sometimes it actually works.

Another problem we stumbled onto just recently is that the background color has an effect on this also. A white background seems to reflect off the pin and change how you perceive the pin in the center. That's where the green back­grounds are coming from.

So l'm not sure I can say that this system is the best. For now it is working very well for me. It continues to evolve and may be different next year. Hope­fully this will be of some help to people.

Bevel Up: So after I read Paul's explana­tion, f got to thinking about that physics professor and his light experiment. I went down to the basement and dug out one of the grandkids' toy balls, and then just to see what would happen, I made a round disk out of black con­struction paper the exact same diam­eter as the ball. Then I put them both on the ends of a couple of pencils and clamped them in a vise on my work bench, turned off the lights, and shined a 100 watt work light straight at the vise with a piece of white board set nine inches behind the ball.

The result was weird, interesting, per­plexing. confusing, and bemusing. Jn short, I didn't know what to make of it. When you stand about three or four feet away and you shine the light on the ball and disk, what you get is a pair of fuzzy sort of round shadows about three inches wide (about the same actual di­ameter as the ball and the disk). But in­side those fuzzy shadows are much more distinct secondary shadows with sharp. dark edges about two and a quarter inches across with a much lighter center. As you step closer with the lamp the fuzzy shadow gets bigger and the sharp edged shadow with the lighter center gets smaller until the sharp centers dis­appear altogether. The interesting part is that the sharp center shadow for the flat disk is less than half the size of the center shadow for the ball. Look at the pictures - you can see what I'm saying better than I can describe it.

You get the same effect using a cyl­inder and a flat blade. The smaller the diameter of any of these objects, the closer you have to get with the Light to make the effect apparent. What the heck does this mean? Is it better to use a ball or a disk for a front sight? Should you use a round post instead of a flat-faced blade? The possibilities boggle the mind.

Bevel Down: In case you haven't fig­ured it out yet, he didn't major in phys­ics either. He can shine all the shop lights he wants to at rubber balls and he still won't know what's going on with his sights.

I think to do things right you need to use a focused beam of light, like a slide projector or laser beam. And then do some measuring and make calculations - stuff like that. rm not a professor ei­ther, though, and I'm not going to try to act like one in my spare time in the base­ment, lecturing to the cat and writing formulas on a blackboard.

Instead, since we can't quite figure it out, we're going to ask our more bril­liant readers to help us out with this light question. If there are any physi­cists (quantum or otherwise) out there who can explain bow or how much light can bend around an object like a sight blade vs. a bead or post, we welcome your contributions!

This stuff is really complicated, but I think if we got a good answer, it might help some of us win a match now and then. See ya next month!