Author Topic: Sighting error  (Read 1185 times)

Offline Mike C

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Sighting error
« on: May 25, 2019, 02:51:53 AM »
Just how close can you hold (from the bench) with our primitive sights? When you look at a group you wonder how much do you attribute to sighting error and how much to all the other variables. Has anyone ever tried to quantify sighting error?
Mike C


100 yards
"Better to remain silent and be thought a fool than to speak and remove all doubt."  A. Lincoln

Offline Bob McBride

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Re: Sighting error
« Reply #1 on: May 25, 2019, 03:30:26 AM »
I shouldn’t have read this post three beers in after brushhogging all day. 🤯
-Bob

My Highland ancestors were sentenced to ‘Transportation’ in lieu of death by King George after the Battle of Culloden. Serving time in Dixie since 1746.

Online msellers

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Re: Sighting error
« Reply #2 on: May 25, 2019, 05:25:52 AM »
I can't recall the values and equations used to get them, but a competitive shooter I grew up around said that a hair width on the sight picture would make for a missed x at 100. Sure wish i had paid better attention to him and a few others when they talked. I would guess that it would be a fairly simple to quantify for a given gun, if ome is somewhat mathematically inclined.
Mike

Offline Flint62Smoothie

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Re: Sighting error
« Reply #3 on: May 25, 2019, 06:58:54 AM »
Here's what some competition shooters and instructors do. The Brits even designed one in WW2 that would 'shoot' a pencil tip at the scaled down target..

Bench an UNLOADED rifle so it can't move. At 25-yards, you sigh, but have someone 'move' a 6" black bullseye around for you, you telling them ... Up, left, little more left, etc., etc., until YOU think it is aligned perfectly with or to the sights.

Tell your helper - 'mark it' and they stick a sharp pencil through the center to make a mark on the paper. Repeat 4 or 9 more times ...when done, that is your 'sighting' group.
All of my muzzleloaders will shoot into a ragged ~1/2" hole ALL DAY LONG ... it's just the 2nd or 3rd or other shots that tend to open up my groups ... !

Offline Mike C

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Re: Sighting error
« Reply #4 on: May 25, 2019, 03:00:17 PM »
Flint,
I had thought of a similar approach at a longer range using a laser and a cell phone connection but I could not find a laser intense enough and focused enough to work. My guess is that 1 moa would be about as precise as one could be with open sights.
Mike C
"Better to remain silent and be thought a fool than to speak and remove all doubt."  A. Lincoln

Offline Hungry Horse

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Re: Sighting error
« Reply #5 on: May 26, 2019, 02:36:06 AM »
This is another example of how our forefathers eliminated unnecessary decisions by making things simple. Almost all antique muzzleloaders that haven’t had the original sights monkeyed with by a modern expert, have a very small blade, or barley corn, front sight, that fills a shallow notch in the rear sight with very little or no  light showing around it. This minimizes sight error. With that problem eliminated, they could concentrate on elevation if the shot was beyond the normal range.

  Hungry Horse

Offline Daryl

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Re: Sighting error
« Reply #6 on: May 30, 2019, 12:56:57 AM »
That is a GREAT 100yard group, Mike.

I have heard of shooting 2-shot groups, then measuring c to c of those two shots, for up to a dozen shots. Then, adding up all those
2-shot groups and finding the average by dividing by the # of 2-shot groups.
The author of that method said it was more accurate in telling what THAT load was doing, than trying to hold it all together
for 5 or 10 shots and measuring c to c of the widest holes. He noted that method just gave you a measurement of your 2
worse 'pulled' shots in the actual group - or something like that. It does make sense for testing the actual accuracy of a
particular load by discounting overall c to c measurements which include screw-ups.
Of course, this simply is something else to test. LOL

Kinda like these groups - what is that load capable of? Is it the c to c or the actual measurement of the hole of 4 out of 5 "good" shots?
These are all 5 shot groups. The older I get, the more often this happens. The bottom targets were shot with "reclaimed" patches from my 14 bore rifle.





The bottom .60 cal. target used the .034" patches I used on the left hand target from my 14 bore rifle. These, also at 50yards.


« Last Edit: May 30, 2019, 01:07:54 AM by Daryl »
Daryl

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Offline kudu

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Re: Sighting error
« Reply #7 on: May 30, 2019, 07:20:51 PM »
Flint 62 smoothie has it right!
 their is a article in Muzzelbast about how to do it.

I believe you move the target for the sighter over a UNMOVABLE BACKER polk a very small pin hole in target Bullseye and then mark the Immovable backer thru the little hole about 6 times should do it.

You DONT MOVE THE GUN at all just look thru the sights call out to your Buddy when the target is perfect to your eye and mark thru the target bullseye onto the backer.

Move the target offcenter and Realign with sights and your Buddy and repeat

When your done you should have very small dots on the backer that are in a PATTERN . this is your best SIGHT PICTURE.

Ive done this with someone but at 40 yards youll be surprised Try It.

Offline Sharpsman

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Re: Sighting error
« Reply #8 on: May 31, 2019, 11:42:44 PM »
At 60 yards after finalizing a zero I don't need to take any measurements. Looking is good enough!

.54 Hawken Flintlock by Sharps Man, on Flickr
"There ain't no freedom...without gunpowder!"

Offline Darkhorse

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Re: Sighting error
« Reply #9 on: June 01, 2019, 10:31:14 AM »
I don't understand the purpose of what y'all are trying to accomplish. I do agree sighting errors are caused by things like wind or light conditions but I couldn't start to quantify those errors.
Seriously guys this is the way I look at it. My rifles are capable of shooting all it's shots into one hole to at least 50 yards if I the shooter does my part. So when working with loads I use a target I like as my standard. And I'm very hard on myself about my shooting.
If I really want to see how my load performs day to day I would shoot a 3 or 5 shot group each day, at the same target, for say 5 days then study the target real good. Each day I'd write down the weather conditions. I would consider the weather changes as my sighting errors.
Beyond that I agree with "Sharpsman", I don't need to take any measurements, I just look at my target.


« Last Edit: June 01, 2019, 06:48:31 PM by Darkhorse »
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Offline Nhgrants

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Re: Sighting error
« Reply #10 on: June 01, 2019, 02:32:45 PM »
Could some of this be a result of something other than sight picture error?
Up and down from breathing and left and right from trigger squeeze?

Offline Daryl

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Re: Sighting error
« Reply #11 on: June 01, 2019, 04:47:56 PM »
When looking through high powered glass,  at a mere 100 meters, my heart beat (has to be in my cheek)
 moves the cross-hairs almost an inch now. I have to time the shot to 'between' beats.  If I let the shot off
 at the wrong time, I add up to 1" to my group width. I do not had high blood pressure, either, as it constantly
 runs 120/70 when tested weekly, at the store. My Dr. gets the same results with his machine.
With open sights, the movement is not there. That does not mean it isn't still happening.
Daryl

"a gun without hammers is like a spaniel without ears" King George V

Offline OldMtnMan

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Re: Sighting error
« Reply #12 on: June 01, 2019, 06:58:42 PM »
If I can get a target to look like Sharpsman at 75 yds offhand. I'm ready to hunt.
Pete

Offline smylee grouch

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Re: Sighting error
« Reply #13 on: June 01, 2019, 07:06:45 PM »
Boy o boy this science of shooting has lots of variables. It looks like your sighting group and shooting group could still be quite different even though you look through the sights the same for each group.

Offline Darkhorse

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Re: Sighting error
« Reply #14 on: June 02, 2019, 09:50:19 AM »
Sometimes a less than ideal group is not caused by a sighting error at all. Let us look at the much despised as useless, bench rest shooting for a tight group. To put it simply, if you have poor form, if you don't know how to shoot benchrest, and if you can't build a solid shooting platform then you can't consistently shoot those tiny groups.
When I build my shooting platform and sandbag my rifle then I will (with unloaded rifle), cock my rifle and take careful aim at a bull then squeeze off the shot. If the sights have moved off the target then that is where your rifle will hit. The trick here is to work with your platform and your form until those sights never move when you take the shot. A less than ideal group here is not caused by shooting error, maybe shooter error is a better word.
American horses of Arabian descent.

Offline Daryl

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Re: Sighting error
« Reply #15 on: June 03, 2019, 04:46:09 AM »
It is very difficult to work up an accurate load if you have poor bench form or bench ability - absolutely correct, Darkhorse.
Daryl

"a gun without hammers is like a spaniel without ears" King George V