Pete mentioned sighting error. I thought I had read about it, and put it in the don't-matter-much category. I asked Rudi, and he sent me the Rifleman article-Factors of Sighting Error, by L. F. Moore, April 1977. This was from the old days, when it sometimes took more than 15 minutes to read a Rifleman. Anyhow, it looks like there isn't much sighting error after basic equipment and practice is correct. I remember noting that there isn't much difference in accuracy after sight radius exceeds 24", and used this info to make my tube sight.
Everything you want to know, from Rudi, for a few bucks. What a deal!
joe b.

Col Whelan gave a good sum of of sighting error.  I will shorten it.

"The unaided eye can only distinguishing diferences between two objects to 1/100 inch. In pratice that's 1 moa  So the best of iron sights have a built in error of 1 moa"

" A telescope reduces this error by the power of the scope, That is a 10 power scope will read to 1/10 of moa. 20 power 1/20 moa etc."

I have found this to be accurate.

Boats

Boats

Boats,

  I'll go along with the scope reducing the amount of error, but also have to agree with Horsefly in that a good apperture front and rear sight will distinguish better than MOA.

  If you will recall I mentioned I can resolve the 25 ring of the ASSRA target at 200 yds. That's 1 1/2". Plus I can resolve the 25 ring at 100 yds. which is 3/4". That right there is under MOA.

  But, I would suspect shooters like David Tubb can resolve finer than that.

  Now this is with the naked eye. With a good iron sight system this resolution would be even better. A crude test for this would be to form a small circle with your forefinger, and vary the size and see what happen. Things that look fuzzy to you with the unaided eye will sharpen up when you adjust the hole just right.

  This is the same way that an apperture rear sight works with a Hadley eye cup. If you have, say, a Gehmann fully adjustable rear and front sight it would amaze you how much sharper, and clearer the target will be when both are adjusted correctly. Doing the PSE test, I mentioned several messages back, many years ago, I at that time had a PSE of 5/8" at 100 yds. This is better than the 3/8" PSE at 50 ft. I had when I was on the school shooting team 45 yrs. ago. But then I've shot a lot of irons in the meantime.

  An example of how resolution works when shooting...... I hate the red bulls that are on one side of the ASSRA targets because even when I look thru them with a decent apperture sight the edges of the bull are not distinct. So whenever possible I shoot the black side as the edges of the bull are nice and sharp and it's easy for me to center the bull up in my sights. My scores show it to with the red bulls scoring less than the black.

  Now here's the kicker. Probably the best shooter in our club shoots the red side and says he sees that best. Yet he claims that he doesn't see anything as clearly as he did 10 yrs. ago.

  So, no matter how good the sights it really boils down to what your eyes can resolve, and that's something each person has to find out for themselves.

PETE

Jerry,

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  Amen!

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  If I have to shoot red bulls I like to shoot the one's the NMLRA puts out. They have just a tint of black in them, and for me at least, show up about as well as a straight black one. These will also show .22 holes at 200 pretty well.

PETE

Joeb,

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  Obviously you're not familiar with the ASSRA targets. So..... The iron sight, 200 yd., 25 ring, is white spot 1 1/2" in diam. and is in the center of a red/black bull 12" (approx.) in diam.

  In fact IIRC on all ASSRA targets the 25 ring is white, so I'm not sure how you can talk like you do later in this post and not know this?

  When this target is posted at 200 yds. I can distinguish this white spot from the surrounding red/black bull. From discussing this with the guys in our club it appears that about 1/2 can pick this out and the rest can't. The 100 yd. offhand targets 25 ring is a 3/4" white spot set in a 6" red/black bull.

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  And... If you'll look at the size of the ASSRA targets that I mention above you'll see these sizes for the bull have been considered pretty much the standard for over a 100 yrs. 
  I would think that almost a perfect score would have to be shot at 200 yds. these days in order to keep in the running. 30 yrs. ago when I was a lowly Marksman in High Power I could shoot into the low 190's. That's a pretty big target!

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  To a certain extent I think this is true, but a great deal depends on two things. The distance and what your eyes can resolve. As I mentioned before I don't feel especially handicapped with irons against a scope at 100 yds. because I can "shade" the sights well enuf to keep up with the rapidly changing conditions we normally experience at our range. At 200 yds. tho I can't resolve things fine enuf to be able to change the position of my sights the 1/8" or 1/4" sometimes necessary.

  I freely admit there are people out there who are far better at resolution than I am. The two people you mentioned who shot 250's on the ASSRA target are certainly two of them.

  I'll have to ask around to see if any of the better shooters in our club have ever shot a 250 with irons at 200 yds. in registered competition. I wouldn't bet on it, but know of one guy who has shot a few with a scope. My personal best is a 244 with irons and a 247 with scope at 200 yds., in competition.

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  Neither can I if the center is the same color as the rest of the bull. The reason you can hit it tho is that with a good set of appertures, front & rear, your resolving power goes up by a good percentage (rember the finger trick), and you are easily able to center those appertures up around the bigger bull.

  As you know, the 100 yd. Small Bore Rifle target is all black, including the 1" X ring. Using a CMP legal AR-15 I can keep all shots inside or touching the X ring. So even tho I can't see the X ring it's easy enuf to hit with fairly decent sights.

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  Naturally! The thing that's keeping it from happening is for the same reason we don't see much in the way of offhand competition. Age!..... IIRC, I think someone posted quite a while ago that the average ASSRA members age was in the low 60's. That reduces down to physical conditioning, and eyesight as the causes of not as much interest in irons over scopes, and lack of interest in offhand.

PETE

Joeb,

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  It seems you're not reading my messages very well, or you have a very short attention span. I covered the "why" several messages back. So, I'll just keep this short......

  Being able to resolve small objects is necessary to being able to "see" the edges of that big black bull. If you can't "see" the edge clearly you can't center the bull up in your sights. This is why I prefer the black over the red bull, and will shoot better scores with the black.

  If you have something along the order of Gehmann front and rear sights you can pretty well adjust them so the bull is nice and sharp unless you have really bad eyesight. But, in games like BP Shilouette you aren't allowed to have that type sight, as far as I know, and I don't see anybody locally using them in Schuetzen, so don't know if they are legal or not. On top of the Gehmann's you can add any number of colored filters and polarized lenses to help. Even put in prescription lenses. All this allows you to shoot well into old age when the eyes ability to focus and resolve things goes downhill. But......

   In CMP (service rifle) competition you are only allowed an apperture rear and open post front sight. So, in order to be able to "float" the bull at High Power ranges the better you can resolve the edges of the target the better your score will be. I know guys in their 70's still shooting it and doing as well as ever, and I know guys in their 50's who've quit because they can't "see" the bull.

  So, depending on the game you're playing, and the sights allowed, will depend on what level of eye resolution you will need to be successful.

PETE

Boats,

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  I certainly won't disagree with you. I've said virually the same in numerous messages on this Forum. But apparently some don't believe in the possibility that people have a PSE. I can see why since your eyes age, and with it the resolving power, so slowly that if you don't do the test you mention, every few years or so, you won't be able to tell the difference. All that will show up is that for some reason your scores go down. But that will be slowly to.

  I recall back when I was shooting Bullseye pistol competitively 35 yrs. ago. Man! Those iron sights were clear as could be. Best I could do was Sharpshooter till I got out of it. About 5 yrs. ago I got back into it again. Sights didn't look quite as I remembered them but my scores were pretty good. Even better than they were back then (high Expert), so just figured I didn't recall things right.

After about a year with no improvement I got into a conversation with some of the older guys in the club about how using a dot sight had really helped them keep on shooting in their class. They finally talked me into putting one on my guns, and like they said, it easily added five points to my score on every target. Enuf to bump me up into Master Class.

  So, unless you're one of those fortunate individuals whose eyesight doesn't deteriorate with age, what your eye can resolve, even with 20/20 vision, will go downhill over the years.

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  The first time we did this on the rifle team I thought it was the oddest thing that even at 50 ft. there were substantial differences in the "group" size between individuals. But after reading a little about it, and talking to my eye doc, I learned that, as in everything else, people are individuals and some are better than others.

  You can improve your ability to resolve things quite a bit thru practice. Dale53 has been writing an interesting series of articles in the ASSRA Journal on using the air rifle during the Winter to keep in practice for offhand. Altho he doesn't mention it, as I recall, part of this practice is to keep his eye in to. I've found that if I don't practice with iron sights during the Winter that it takes me about two weeks in the Spring to get my "eye" back.

PETE

Boats,

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  Now if I can only take this advice.  I tend to ride the shot to long and know I should break it faster, but having a tendency to chicken finger and wanting to get the best shot I can, it's one tough habit to break. Part of my problem is that I seem to be blessed with eyes that don't tire/fade fast, and I have the ability to hold the shot for long periods of time, so altho I know I should break it faster, I know I can hold long enuf for the best shot. The real problem is that I get away with this more times than not.

  One thing I've noticed is that if I eat a heavy meal a coupla hours before a match that my eyes aren't as sharp as when I eat a light meal, or nothing at all till after them match.

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  Have to laugh about this as I'm not steady enuf for it to make any difference if I'm using irons or a scope. I read how the old timers said to put pressure on the trigger as the sights move deeper into the bull, and hold it as they swing out. Repeat as necessary till the shot breaks. Yeah! Sure!  My sights go thru so fast my squeeze doesn't even start till it's out in the white on the other side!

  Gonna have to try the other trick I read they do. Sandpaper your trigger finger to increase the sensitivity. Some times they would get carried away to the point their finger would bleed.

PETE