6X5 SHOOTERS I WOULD LIKE YOUR INPUT PLEASE...

jbell

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    There has been some talk on the 6X5 about a standard to use to determine a CTC measurement. I have always used 0.222” as that is what the original discussion way back when this all started kinda settled on. Some people have different opinions and that is great, I am open to anything. I do agree with implementing a “standard” so every submission is as equal as possible (for comparasion sake). I will implement this in the next version which I will start 01/01/21, so we have time to talk it over and decide.

    I would also like to suggest that we all start submitting measurements down to the thousandth. I know many people will argue that you can not accurately measure to that resolution, which may be true but I will argue that being off 0.001”- 0.002” from actual is much closer than being off by 0.009” at very best if you are only measuring to the hundredth as opposed to getting as close as you can to the thousandth. Just my opinion, thoughts?

    On the topic of a standard I think 0.222” should be the very largest we use. I have NEVER seen a bullet hole measure larger from a rimfire. I think this is mainly because most bores Have a grove diameter of 0.222” or smaller, at least in precision barrels.

    Thank you for your time in advance in helping me make the 6X5 thread as good as it can be!
     
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    Near miss

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    I think .222 sounds good.
    But I do like measuring with software like TargetScan also.

    What I have small problem understanding is measuring to the thousand. I get it for internet competitions, but I myself do not see 6x5 as a competition, more like a gun benchmark. Because everybody gets as many tries as possible and the mindset in the thread is not competition-like either.

    But I am for measuring the groups as accurately as possible, just do not know if the added digit will give much more info we need.
    In some cases like 50yd it could be useful but I think the salt of 6x5 is in the 100yd. That is just my opinion also.
     

    barronian

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    @jbell I would vote for using something like Ontarget TDS /Ballistic-X.
    If one really must use calipers then subtract a measured bullet hole size. The difference between using software(correctly) and a caliper - .22x can be so large (especially at 50yds) that it makes comparing the results really unfair.
    Also with the way that accuracy and precision is improving we will get the situation where 50yd, caliper - .22x, is giving negative numbers ....

    there are examples where the difference between a submitted group size measured by caliper - .22x and the same group measured by OnTarget is around 0.05".
    At 100m or 200m this difference possibly isn't worth arguing over but for those that are towards the top of the 50yd listings that could move your ranking 5 or 6 places !

    There isn't anyone else who shoots .22 where i live so i compete against myself and compare against the 6x5 entries to see how I'm doing. I'm quite prepared to measure the 6x5 entries myself so that i can compare them against my own efforts. I could, of course, adopt the caliper - .22x standard to make the comparison easier, but I've never been good at deluding myself - i want to know what my 'real' accuracy is.
     

    Rimfireshooter99

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    jbell, a couple of examples using a caliper and measured two different ways; Center to Center with no subtraction and Edge to Edge, then subtracting 0.222.
    So which widths would I report for the 6x5? CTC or ETE?

    Bull 3 - 0.161 ETE vs 0.226 CTC
    Bull 5 - 0.153 ETE vs 0.239 CTC
     

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    Rimfireshooter99

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    The pictures above are from a target with 65 lb cardstock, and the holes have a dark ring where the bullet pushed through, but did not cut the stock from edge of the round to edge of the round. So the paper hole will always (in my experience) be smaller than the bullet diameter. Another factor to consider in describing how to measure for 6x5.
     
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    Sixgunjeff

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    jbell, a couple of examples using a caliper and measured two different ways; Center to Center with no subtraction and Edge to Edge, then subtracting 0.222.
    So which widths would I report for the 6x5? CTC or ETE?

    Bull 3 - 0.161 ETE vs 0.226 CTC
    Bull 5 - 0.153 ETE vs 0.239 CTC
    If there is separation between bullet holes measure with a dial caliper from the outside edge of one of the farthest holes to the inside edge of the other. This gives a accurate measure of group size CTC regardless of bullet hole size. If the group is a single enlarged hole use the parts of the dial caliper that are intended to measure inside diameter and carefully measure the the largest part of the hole without tearing the paper then subtract .222". This is about as good as can be done to keep the measurements fair, accurate and consistent. Software measurements are not consistent nor accurate because it relies on the exact input of the bullet hole diameter which is not being done. Example, entering unfired bullet diameter of .224 and the software looks at bullet holes in paper that are actually. 178" yet the software "thinks" that they are .224". Actual group size is no where close to what the software measures.
     
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    Rimfireshooter99

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    There has been some talk on the 6X5 about a standard to use to determine a CTC measurement. I have always used 0.222” as that is what the original discussion way back when this all started kinda settled on. Some people have different opinions and that is great, I am open to anything. I do agree with implementing a “standard” so every submission is as equal as possible (for comparasion sake). I will implement this in the next version which I will start 01/01/21, so we have time to talk it over and decide.

    I would also like to suggest that we all start submitting measurements down to the thousandth. I know many people will argue that you can not accurately measure to that resolution, which may be true but I will argue that being off 0.001”- 0.002” from actual is much closer than being off by 0.009” at very best if you are only measuring to the hundredth as opposed to getting as close as you can to the thousandth. Just my opinion, thoughts?

    On the topic of a standard I think 0.222” should be the very largest we use. I have NEVER seen a bullet hole measure larger from a rimfire. I think this is mainly because most bores Have a grove diameter of 0.222” or smaller, at least in precision barrels.

    Thank you for your time in advance in helping me make the 6X5 thread as good as it can be!
    jbell, a thought. Since measuring to the hundredth's of an inch is challenge, would it make sense to report all data to the nearest tenth of an inch, rounding up or down from the hundredth of an inch? After measuring a couple bulls this morning, and seeing the difference in width as measured CTC or by ETE and subtracting 0.222, maybe it's just easier to report shooter averages as follow (Note: for 50 yard averages):

    </= 0.1 inches
    </= 0.2 inches
    </= 0.3 inches, and so forth?

    I would propose that this is an accurate enough measure of accuracy for a 6x5 group size and prevents us from "splitting hairs" over measurements that are very challenging to do accurately. A 5-shot group that is less than or equal to 0.2 inches is pretty darn good shooting, so I'm not sure if there is real value in reporting to more sig figs than a tenth of an inch.

    Just a thought for everyone's consideration...

    Thanks!
     
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    Rimfireshooter99

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    If there is separation between bullet holes measure with a dial caliper from the outside edge of one of the farthest holes to the inside edge of the other. This gives a accurate measure of group size CTC regardless of bullet hole size. If the group is a single enlarged hole use the parts of the dial caliper that are intended to measure inside diameter and carefully measure the the largest part of the hole without tearing the paper then subtract .222". This is about as good as can be done to keep the measurements fair, accurate and consistent. Software measurements are not consistent nor accurate because it relies on the exact input of the bullet hole diameter which is not being done. Example, entering unfired bullet diameter of .224 and the software looks at bullet holes in paper that are actually. 178" yet the software "thinks" that they are .224". Actual group size is no where close to what the software measures.
    Good point. I tried to remeasure the two example bulls after I read your post. Bull No. 3 has a clover-leaf pattern and has no inner edge to use as a measuring point. I was able to measure Bull No. 5 and attached the picture below.

    What do you think about just using the outer edge of the group at the widest point (whether that is the outer edge of two holes, or the outer edge of a larger whole), and reporting to the tenths of an inch as in the above post? Keeps it simple, easy to group the data into the buckets suggested.

    Also, I agree with your comments on software. I have used Ballistic X and you have to set an inch reference for the software can calculate the diameter of a group. A little error on that, and the measurement will be off for the group size.

    Good thoughts!
     

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    padom

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    All of these points you guys bring up is exactly why just picking a standard number to subtract from outside to outside. The whole point is to be consistent and easy for everyone to do. No rounding, etc etc. If you want to take measurements other ways for your own use you have the target right there in front of you, its that easy. But for purposes of simplicity and comparison from one target to the next, outside to outside black/smudge mark minus .222 or .220 or whatever the final consensus is makes this very easy for everyone. And I agree, since we are subtracting a 3 digit number, the measurements should be to the .001....... My 2 cents. Im good with whatever you all choose for that standard number.
     
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    Rimfireshooter99

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    All of these points you guys bring up is exactly why just picking a standard number to subtract from outside to outside. The whole point is to be consistent and easy for everyone to do. No rounding, etc etc. If you want to take measurements other ways for your own use you have the target right there in front of you, its that easy. But for purposes of simplicity and comparison from one target to the next, outside to outside black/smudge mark minus .222 or .220 or whatever the final consensus is makes this very easy for everyone. And I agree, since we are subtracting a 3 digit number, the measurements should be to the .001....... My 2 cents. Im good with whatever you all choose for that standard number.
    padom, can I ask you, I have always measured CTC, and tried to do my best to make sure the caliper ends are centered in the holes. My question is, this is the first time I have measured edge to edge, and then subtracted 0.222. Would you expect the values to be different? I was surprised when I did the edge to edge with subtraction, that the numbers were not close to the center to center numbers? Thoughts?
     

    padom

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    padom, can I ask you, I have always measured CTC, and tried to do my best to make sure the caliper ends are centered in the holes. My question is, this is the first time I have measured edge to edge, and then subtracted 0.222. Would you expect the values to be different? I was surprised when I did the edge to edge with subtraction, that the numbers were not close to the center to center numbers? Thoughts?
    Yep, absolutely different. And, I dont care how good you think you are there is no same 2 measurements by 2 people measuring CTC in a hole with no definitive point to set your calipers to... This is why the OTO and subtract method is used.... You are missing the point of this discussion. Its not to make the OTO and CTC numbers the same. Its to set a standard method to which all can do with comparable results.
     

    rick137

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    I would like to see a gallery of single bullet holes from different target material, backing and ammunition. People could comment on what they consider to be the "edge" of the bullet hole. Perhaps there would be unanimous agreement, perhaps not. But if people cannot agree on what is the edge, then comparisons are impossible. Apples and oranges.
     

    BillOH

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    I haven't had much luck using Ballistic-X on my I-phone X. Every time I touch the screen to place a mark, the mark moves when I lift my finger. Also it is hard to get a perfect picture of the target.

    I have been measuring out side to outside of black grease ring, making sure it is as honest as I can make it. Then subtract .222. I'll get some pictures. I use a Lyman dial caliper and it's no problem measuring to .001".
     

    Rimfireshooter99

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    Yep, absolutely different. And, I dont care how good you think you are there is no same 2 measurements by 2 people measuring CTC in a hole with no definitive point to set your calipers to... This is why the OTO and subtract method is used.... You are missing the point of this discussion. Its not to make the OTO and CTC numbers the same. Its to set a standard method to which all can do with comparable results.
    I would beg to differ, I am not missing the point. I get it, but I was surprised that the number were so different. Try not to be a dick about this and just help out with a question. Thanks!
     

    Rimfireshooter99

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    I would like to see a gallery of single bullet holes from different target material, backing and ammunition. People could comment on what they consider to be the "edge" of the bullet hole. Perhaps there would be unanimous agreement, perhaps not. But if people cannot agree on what is the edge, then comparisons are impossible. Apples and oranges.
    rick137, I agree. I've always used the edge of the paper surrounding the hole, and you are also correct, different paper weight will likely react differently to a bullet passing through.
     

    padom

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    I would beg to differ, I am not missing the point. I get it, but I was surprised that the number were so different. Try not to be a dick about this and just help out with a question. Thanks!
    Your 5 posts in this thread say otherwise when the OP asked what NUMBER do you want to use since he wants to use a standard and asked about measuring to the .001. So your 5 posts about what you do and how you measure to the center of a hole and continuing about measurement differences from what the OP is asking vs what you do. We all know there is a different, you know that by taking the measurement. YOU ARE MISSING THE POINT OF THIS THREAD. Now you want to see me be a dick I can give you what you ask for. Nobody was being a dick and your question was answered. Now get back on topic.
     
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    jbell

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    I think .222 sounds good.
    But I do like measuring with software like TargetScan also.

    What I have small problem understanding is measuring to the thousand. I get it for internet competitions, but I myself do not see 6x5 as a competition, more like a gun benchmark. Because everybody gets as many tries as possible and the mindset in the thread is not competition-like either.

    But I am for measuring the groups as accurately as possible, just do not know if the added digit will give much more info we need.
    In some cases like 50yd it could be useful but I think the salt of 6x5 is in the 100yd. That is just my opinion also.
    I think measuring to the hundredth of an inch leaves too much variation. IMO you will be closer to the actual group size when measuring to the thousandth even if your off by a thousandth or two than if your only measuring to the hundredth. But it all comes down to who is doing the measuring I suppose. Maybe I am just very used to making precise measurements with my job.

    @jbell I would vote for using something like Ontarget TDS /Ballistic-X.
    If one really must use calipers then subtract a measured bullet hole size. The difference between using software(correctly) and a caliper - .22x can be so large (especially at 50yds) that it makes comparing the results really unfair.
    Also with the way that accuracy and precision is improving we will get the situation where 50yd, caliper - .22x, is giving negative numbers ....

    there are examples where the difference between a submitted group size measured by caliper - .22x and the same group measured by OnTarget is around 0.05".
    At 100m or 200m this difference possibly isn't worth arguing over but for those that are towards the top of the 50yd listings that could move your ranking 5 or 6 places !

    There isn't anyone else who shoots .22 where i live so i compete against myself and compare against the 6x5 entries to see how I'm doing. I'm quite prepared to measure the 6x5 entries myself so that i can compare them against my own efforts. I could, of course, adopt the caliper - .22x standard to make the comparison easier, but I've never been good at deluding myself - i want to know what my 'real' accuracy is.
    I see what you are saying. I guess both systems (manually measuring and electronic measuring) all comes down to the person doing the measuring.
     

    jbell

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    Software measurements are not consistent nor accurate because it relies on the exact input of the bullet hole diameter which is not being done. Example, entering unfired bullet diameter of .224 and the software looks at bullet holes in paper that are actually. 178" yet the software "thinks" that they are .224". Actual group size is no where close to what the software measures.
    This is my hang up with software, or at least the software I have messed with.
     

    KML7201

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    When using a caliper I always measure from the outer edge of the black ring of the two holes that are furthest apart and subtract the diameter of one bullet. Trying to eye up the center of a hole and keeping the caliper there for a measurement leaves room for more error. I think measuring from the outer edge of the black rings and subtracting .222 is a good standard. Just my 2 cents.
     

    jbell

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    All of these points you guys bring up is exactly why just picking a standard number to subtract from outside to outside. The whole point is to be consistent and easy for everyone to do. No rounding, etc etc. If you want to take measurements other ways for your own use you have the target right there in front of you, its that easy. But for purposes of simplicity and comparison from one target to the next, outside to outside black/smudge mark minus .222 or .220 or whatever the final consensus is makes this very easy for everyone. And I agree, since we are subtracting a 3 digit number, the measurements should be to the .001....... My 2 cents. Im good with whatever you all choose for that standard number.
    Exactly my thoughts, but I am not trying to force peoples opinion or this decision in any particular direction.
     
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    jbell

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    Your 5 posts in this thread say otherwise when the OP asked what NUMBER do you want to use since he wants to use a standard and asked about measuring to the .001. So your 5 posts about what you do and how you measure to the center of a hole and continuing about measurement differences from what the OP is asking vs what you do. We all know there is a different, you know that by taking the measurement. YOU ARE MISSING THE POINT OF THIS THREAD. Now you want to see me be a dick I can give you what you ask for. Nobody was being a dick and your question was answered. Now get back on topic.
    Not to butt into y’all’s discussion especially when you guys didn’t ask my opinion. However I think deciding on how fine to measure the target is not a bad idea before we decide what standard we use to determine CTC...
     

    jbell

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    jbell, a couple of examples using a caliper and measured two different ways; Center to Center with no subtraction and Edge to Edge, then subtracting 0.222.
    So which widths would I report for the 6x5? CTC or ETE?

    Bull 3 - 0.161 ETE vs 0.226 CTC
    Bull 5 - 0.153 ETE vs 0.239 CTC
    I think the inconsistencies your seeing are because you are not measuring at the correct part of the bullet hole when measuring the ETE. Measure from the outer edge of the black ring, that is part of the bullet hole (group) also. Let me get some pics to see if I can explain it.
     
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    KML7201

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    When using a caliper I always measure from the outer edge of the black ring of the two holes that are furthest apart and subtract the diameter of one bullet. Trying to eye up the center of a hole and keeping the caliper there for a measurement leaves room for more error. I think measuring from the outer edge of the black rings and subtracting .222 is a good standard. Just my 2 cents.
    Another option. Measure from the outer edge of the black ring to the inner edge of the black ring of the two holes furthest apart. No need to subtract anything.
    But that only works if you have separation in your holes so forget Imentioned it.
     

    Sixgunjeff

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    Not to butt into y’all’s discussion especially when you guys didn’t ask my opinion. However I think deciding on how fine to measure the target is not a bad idea before we decide what standard we use to determine CTC...
    Using the
    I think the inconsistencies your seeing are because you are not measuring at the correct part of the bullet hole when measuring the ETE. Measure from the outer edge of the black ring, that is part of the bullet hole (group) also. Let me get some pics to see if I can explain it.
    Using the inside diameter measuring legs of a dial caliper to expand the edges of the hole without tearing the paper works. Try it.
     

    justin amateur

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    I'm not worried about the thousandths Jbell.
    Even if'n ya' were to use Mark I eyeball to measure center to center, to the nearest tenth, it's close enough.
    Measure it in millimeters if'n it makes ya' happy.
    The true value of y'er 6x5 is a long term visual reference of real world results.
    Not some keyboard kommando's 5 shot random act of accuracy,
    followed by the claim "all day long, if I do my part."
    Yeah, right. ;)
     

    Rimfireshooter99

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    Your 5 posts in this thread say otherwise when the OP asked what NUMBER do you want to use since he wants to use a standard and asked about measuring to the .001. So your 5 posts about what you do and how you measure to the center of a hole and continuing about measurement differences from what the OP is asking vs what you do. We all know there is a different, you know that by taking the measurement. YOU ARE MISSING THE POINT OF THIS THREAD. Now you want to see me be a dick I can give you what you ask for. Nobody was being a dick and your question was answered. Now get back on topic.
    Haha. You’re funny. Why not stop telling people what to do and just provide some ideas on what you think would work best.
     

    Jadams

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    When accurately measuring the center to center distance between holes, the diameter of the “tool” that created the hole is irrelevant. I shot in the rain a few months ago and the bullet hole in the wet paper was very small. If I measure outside to outside and subtract the bullet diameter the results are totally inaccurate.
     

    phlegethon

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    Software measurements are not consistent nor accurate because it relies on the exact input of the bullet hole diameter which is not being done. Example, entering unfired bullet diameter of .224 and the software looks at bullet holes in paper that are actually. 178" yet the software "thinks" that they are .224". Actual group size is no where close to what the software measures.
    This is not accurate with the ones I’ve used including Ballistic-X. It isn’t measuring from the outside and subtracting bullet diameter. It’s measuring using a bullet-sized marker on screen. There can be error but it is related only to how closely you position that marker to the center of the hole. You should be able to get that to within a pixel or so—I don’t have time to figure out what that would be at the moment.
     

    BillOH

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    IMG_5276.jpgIMG_5277.jpg

    This is the way I've been doing it. .708 minus .222 = .486. Same group measuring outside to outside and subtracting .222 and also measuring inside edge to outside edge.
     

    Sixgunjeff

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    This is not accurate with the ones I’ve used including Ballistic-X. It isn’t measuring from the outside and subtracting bullet diameter. It’s measuring using a bullet-sized marker on screen. There can be error but it is related only to how closely you position that marker to the center of the hole. You should be able to get that to within a pixel or so—I don’t have time to figure out what that would be at the moment.
    What does it use for a reference to size?
     

    phlegethon

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    What does it use for a reference to size?
    The size of what? The only size reference that would affect the result is the calibration of the size of the paper, usually marking an inch. Again, you should be able to do that to within a pixel or two.
     

    Jadams

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    If a standardized target were used that had an accurate 1 inch reference (could be the out diameter of the scoring ring or simply a printed rule next to each aiming point) and require an image of the targets with each submission, anyone here could use various methods to confirm the group size no mater what size the image is displayed at. Target Scan, Balistic X, using calipers and scaling the image size or using any of the commercial grade imaging equipment and software is possible and simple. Some have been doing that already with the groups that are posted here and that is much of the basis of this controversy. In some cases the claimed center to center distance Is over 20% smaller than actual.
     

    phlegethon

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    If a standardized target were used that had an accurate 1 inch reference (could be the out diameter of the scoring ring or simply a printed rule next to each aiming point) and require an image of the targets with each submission, anyone here could use various methods to confirm the group size no mater what size the image is displayed at. Target Scan, Balistic X, using calipers and scaling the image size or using any of the commercial grade imaging equipment and software is possible and simple. Some have been doing that already with the groups that are posted here and that is much of the basis of this controversy. In some cases the claimed center to center distance Is over 20% smaller than actual.
    Yes but then you don’t know if it was printed at 100% or if the printer was miscalibrated. Personally I don’t really care that much. There is always measurement error. I wonder if the benchrest people have validated their ability to measure group sizes to the thousandth?
     

    Criver600

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    Its not that hard.
    1. In measuring groups fired with calibers for the caliber to be measured, the measurement shall be made from the extreme outside edges of the two widest bullet holes and the actual differential of the larger calibers shall be subtracted from the measurement
     

    phlegethon

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    Its not that hard.
    1. In measuring groups fired with calibers for the caliber to be measured, the measurement shall be made from the extreme outside edges of the two widest bullet holes and the actual differential of the larger calibers shall be subtracted from the measurement
    Try having ten people measure some groups this way, to one thousandth of an inch, and see what the standard deviation of the measurements is. My bet is it will be higher than 0.010.
     

    rick137

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    Metrology. Fascinating topic. Just to add a little more fuel to the fire, what about agreeing on a standard for the accuracy of the measurement. There is the uncertainty of what is the edge and the skill to measure edge-to-edge. For calipers from both edge uncertainty and caliper skill I estimate my accuracy is +/- 0.015" at best. Others I am certain have considerably more skill with calipers and better eye sight.

    Another devil-in-the-details with calipers is calibration. Jaws closed can to set to 0.000" but what at a finite distance apart? Need a calibration block. Perhaps good calipers are accurate to +/-0.001 at distances being measured, perhaps not.

    With software uncertainty in determining center of the bullet hole/black smear as well I am certain several technical issues with the measurement, against including the calibration issue.

    If calculating MOA the accuracy of the distance from the muzzle to the target. Could well introduce more inaccuracy into the MOA than the diameter of the group.

    Subtracting a given number from the measured one does not make the new number any more accurate, just a different number.

    We can all agree that a 5-shot group measuring 0.5XX" ETE is less precise than a group measuring 0.2XX" ETE, but what about 0.325" ETE versus 0.350" ETE? It depends on whether one person is doing the measurements or the measurements are from two or more people. And whether the people are as skilled as @jbell and @padom or not so skilled as myself.
     
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    Tim7139

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    Jul 3, 2020
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    This:
    View attachment 7400031
    As opposed to this:
    View attachment 7400032
    There is about 0.095" difference in the two measures by the way...
    that is absolutely correct.
    A rimfire slug going through the vast majority of paper will not cut a clean hole, it tears the outside radius, thus, you gotta measure from the outside of the smear which is why the best legal plugs(for BR score, are stepped to seat into the hole) bring you right to that edge. When you look at your blow up images it is easy to see you can get pretty damn close to that edge regularly.

    Problem number one, if you go back and review a lot of the shots in those group images, a lot of’em ain’t round due to some unstable rounds. You can see oblong holes so that hurts you......unless you are one of the guys that simply do not account for it.

    problem number two Lots of groups measured with ragged one hole groups not using widest two shots.

    Problem number three, everything here will, best case, end up as a reasonable approximation mostly because the ONLY way to get solid group measurement is with a caliper with a rigid mounted etched reticle, just as is used in CF IBS or NBRSA group matches........zero shooters are going to that trouble.
    Soooooo, long story even longer, everybody will deal with being generally in the neighborhood.
    Reasonable attempts at consistency are to be lauded, the guys that are never going to figure out two holes side by side.....or more, are never going to be .175” or anything close,those guys throw all reasonable attempts at this, off the rails IMHO. They seem past the point of education.
     
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    jbell

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    I see y’all’s point on how easy it is to get lost in the weeds and how difficult it can be being as accurate as humanly possible when measuring rimfire rounds on paper and then calculating MOA. I am right there with ya!

    However I think the point of this discussion isn't how to squeeze the very last drop of accuracy out of our measurements, but rather how can we all be a little more on the same page when submitting measurements. Keep in mind the MAIN point of the 6X5 thread isn’t a competition, it is to get more people interested in precision rimfire. My goal is to grow the sport, share knowledge, provide a welcoming source of information and inspiration for new shooters. The last thing I want to see is making this over complicated and thus turning people away from it.

    So let’s try to keep the final decision fairly simple, easy to do with common measuring devices that most shooters have or at least should have.
     
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    Funcpottr

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    My vote is outside to outside minus .222. With jbell's illustration so I won't screw it up from one time to the next. Do the best you can with what you got and the people getting pissed about 'losing' because 'somebody can't measure right' should get an automatic 0.2225" penalty.
     

    barronian

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    This is my hang up with software, or at least the software I have messed with.
    What does it use for a reference to size?
    they use the reference distance you enter (ie the 1" or 3.65" or whatever you tell the software is a known distance). This defines the absolute scale of the 'picture' - the larger the reference distance the more accurate it will be. The bullet diameter is just used to get a suitable, scaled, ring to display that will give an easy visual match to the bullet holes. Human perception is remarkably good at aligning two circles of near same size - much better than we are at deciding the center or diagonal of a circle.
     
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    barronian

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    My vote is outside to outside minus .222. With jbell's illustration so I won't screw it up from one time to the next. Do the best you can with what you got and the people getting pissed about 'losing' because 'somebody can't measure right' should get an automatic 0.2225" penalty.
    So here is an example of the problem with this approach..
    group.png

    lets assume that i can actually shoot like Padom and others and that the two bullet holes selected are actually my 5 shot group...
    This target was dry, high quality card and the bullet holes are close to full size so the caliper reading (oto) is 0.305" this gives a ctc of 0.305 - 0.222 = 0.083"
    If the target was damp paper then the bullet holes would prob be closer to 0.17" so the caliper reading (oto) would be 0.28" this gives a ctc of 0.28 - 0.222 = 0.058" - close to half of its true size and markedly better 'score' than 0.11". ...

    so depending on the target paper the same group could measure with the calipers - .22x method anything from 0.083" to 0.058" - this is a huge error margin - even ignoring human errors in the process.

    In comparison the software method would give approx the same result in both cases. It may still not be perfectly accurate, but it is more accurate, and dramatically more consistent.
     
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    Near miss

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    I just wanted to add that eletronical scoring should be promoted.

    You can measure reference target length with a caliper or a ruler, the targets are often 1 inch wide.
    Or you can use whatever paper you have and just draw like precisely 2" long line and use that as reference. The longer it is the smaller the error margin is.

    The problem with bad cameras is that on a large piece of paper it WILL distort the image. You should test this by looking if group sizes change depending on if you use reference from center or the edge. This applies mostly when there are multiple groups in the same picture.

    Or you can use standardized targets like Air pistol 10m or air rifle 10m targets and TargetScan software. It works well because the software removes distortion by placing the shots on a matrix determined by the circles.

    And what comes to measuring to the thousands, I myself just record my shots to the nearest tenth of a centimeter, rounding up when unclear. I get no kicks for making my groups appear smaller than they are, I record them just to see my progress.

    There is also the logical problem with sharp measuring, since we do not measure the target distance accurately either. Most just rely that the targets are at 50yds.

    And sliiightly offtopic:
    Also there is problem when we europeans shoot 109 yards, we shoot 9% more distance but our groups are measured with the same standard, even rimfire inaccuracy usually grows 3x per doubled distance.
    So a 1.5" group at 100yds is close to 1.635" at 109 yards.
    In counter if I shot 1" at 109yds I would then multiply it by 0.092 to simulate a 100yd group which would make it 0,92" group.

    Not especially ranting, but pointing out there are some variables that make comparison of groups very hard, even when they would have been measured by the same person to the thousandths.

    The 3x rule is not a set rule, but quite accurate. I have calculated it myself also from accurateshooter article, where a number of different ammo was shot from a Bleiker rifle.
     
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    Quarter Horse

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    There are so many variables that effect the diameter of the bullet hole that there will not be any true consistency in measurement from one target to another and from one individual to another. I started shooting the original 6X5 in 2013. I got a little obsessive about trying to find a medium for targets that would provide some consistency. The only that I can tell is that, under most circumstances, it doesn't reliably exist. Many of the reasons have already been pointed out by other posters.

    I see y’all’s point on how easy it is to get lost in the weeds and how difficult it can be being as accurate as humanly possible when measuring rimfire rounds on paper and then calculating MOA. I am right there with ya!

    However I think the point of this discussion isn't how to squeeze the very last drop of accuracy out of our measurements, but rather how can we all be a little more on the same page when submitting measurements. Keep in mind the MAIN point of the 6X5 thread isn’t a competition, it is to get more people interested in precision rimfire. My goal is to grow the sport, share knowledge, provide a welcoming source of information and inspiration for new shooters. The last thing I want to see is making this over complicated and thus turning people away from it.

    So let’s try to keep the final decision fairly simple, easy to do with common measuring devices that most shooters have or at least should have.

    I have done this for almost seven years and the above is pretty much what it has always been about. I live in a rural area and shoot on the driveway for fifty and a hundred. Further is available by going to a pasture. The performance of other gear and shooters is pretty much what I read here. It gives me a way to gauge my performance and it is greatly appreciated. Originally a technical discussion here would be about something like the deterioration of ammo accuracy as the temperature falls. Now that discussion is more likely to be about chamber dimensions and their effect on reliability and accuracy.

    I have two suggestions for 2021. The first is stop listing "best group" for each 6X5. It tells us very little to nothing and doubles the input for jbell. The second is going back to an earlier day requiring a picture of the rifle and a detailed description. It would tell us a lot about changes in performance. Did you change from a rear bag to a butt spike? Were you shooting a twenty four ounce trigger and now your shooting a four ounce? Have you built a new bench with increased stability? Any dialogue that provides info. is a plus.

    Edge of smear to edge of smear minus .222 has been the standard and should continue to be so.
     

    1moaoff

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    .222
    Seconded!
    And the motion passes!

    Edge of smear to edge of smear
    Seconded!
    And the motion passes!

    Please note the FACTS into the bylaws.

    Also as a note. I rarely measure groups to that degree. However when I am I will often use a plastic drafting circle pattern. Lay it over the target and refernce where I am measuring. Its pretty easy to see and 2 inexpensive patterns can be set on top of one another.
     
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