OK, How do you measure group size? Shooting at a black 3.75 in. bull, the farthest hole is 1.50 in from 10x, would that be a 1.50 in. group, or do I measure from the 2 farthest holes, which would be a little over 3 in.? 5 shot group. Probably a dumb question. I guess I would call it 3 in. group. thanks, chuck
Measuring group size?
- Thread starter chuck-ia
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Phil Coffins
69 Cal.
Many folks measure from the center of each hole to the farthest hole. Where it is on the target is for score but the group is the size of the pattern of holes.
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Measure it outside to outside and then subtract one bullet width. That’s the same as center to center but you don’t have to guess where the centers are.
Want to do it the old way? Try Figure of Merit
https://www.tapatalk.com/groups/bri...y-measuring-figure-of-merit-calcu-t18600.html
https://www.tapatalk.com/groups/bri...y-measuring-figure-of-merit-calcu-t18600.html
Dang Fellas! I’m a better shot than I thought I was !
This whole time I thought a 3 “ group would fit inside of a 3.75 “ black bull......
This whole time I thought a 3 “ group would fit inside of a 3.75 “ black bull......
hanshi
Cannon
The method I've always used is to measure from the outside edge of one to the farthest hole's inside edge. This is better for us "mathematics impaired" shooters. Of course outer edge to outer edge minus caliber is easy to do and just as accurate. And don't forget, you can still lie to your companions as long as they don't see you measure up close.
thanks for the replys, chuck
Pete G
76 Cal.
I am supprised that no one mentioned string measurement, the distance around the outside of all holes.
Col. Batguano
75 Cal.
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While measuring CTC group size is useful, one flyer can radically alter the results I always find that shooting a large number in a group (like say 10-15 shots) is most useful, and measuring outward from what you perceive to be the center. Then divide by the number of shots to get your average deviation from the center. From a practical viewpoint, you're REALLY most interested in what distance you can expect to miss dead center by anyway.
hanshi
Cannon
Mark Herman
50 Cal.
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String measure is not around the outside of the group. String measure is a compilation of all the distances from the X center being shot at and the distance from the X to the center of each hole. Example, 3 shot group:
1 shot is 1/2 inch from center X
1 shot is 3/4 inch from center X
1 shot is 1 inch from center X
Total string measure would be 2 1/4 inches
1 shot is 1/2 inch from center X
1 shot is 3/4 inch from center X
1 shot is 1 inch from center X
Total string measure would be 2 1/4 inches
ResearchPress
45 Cal.
The system used to define the accuracy of rifled arms during Victorian times was the "Figure of Merit".
David
David
Mark Herman
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Not to be argumentative but we are no longer in the Victorian era. This is the way it is done today.
It depends on when the author of the source commenting on the marksmanship was writing. Ned Roberts in The Muzzle-Loading Cap Lock Rifle on page 123 documents three methods of "string measurement"...,
"…, a wooden plug was placed in each hole, a piece of string was held by one end at the center of the cross mark, the string carried around the wooden plugs in the bullet holes, back to the center spot and cut off. This string was then measured and the man whose string measured the shortest was the winner."
"..., but at some later period the method was changed and thereafter they measured with a piece of string from the center of the cross mark to the center half of a round ball which each man provided and which was placed in each bullet in his board. The string was measured, the length set down on paper, the distance of the center of each half bullet from the center cross was measured in the same way and set down; then by adding these measurements the total length of the string was ascertained...,
This was likely eventually found to be rather crude, and so the second method was refined into a third method, which was simply adding more precision, which Roberts writes has been in effect since about 1840, or at the beginning of the Victorian era...,
"..., [the target] is brought to the firing point where some man who has been chosen as the "Measurer of targets," places the target on a piece of paper, pricks a hole with a small "scriber" through the center of the "bud", or center spot, and in the same way marks the center of each bullet hole. Then a pair of dividers are used in measuring the distance from the center of the "bud" to the center of each bullet hole, these distances recorded in inches, eighths and sixteenths, these measurements are added and the total is the "string measurement" of the group of shots. "
Now, if I correctly understand the Victorian "figure of merit"..., it's similar to what Roberts terms the "third method" only the measurements from the center of the target's point-of-aim to the center of the bullet holes are measured, and then added and …, averaged...to judge the mean deviation to be expected of the rifle (if benched for testing) or caused by the shooter (during a contest) ?? The center of the bullet holes from the aiming point is used today to determine group, but...,
when scoring a target do not most methods say if the line of the ring is "cut" by the bullet hole, the higher score is counted? Do not some other methods say at least 1/2 of the hole must be across the scoring line to count as the higher score?
LD
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Mark Herman
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LD,
You are correct in what you posted, however I don't know of any match today that "averages" the string measure after it has been determined. The only reason I can see to do it would be for the shooters determination of his POI average, not the string score.
You are correct in what you posted, however I don't know of any match today that "averages" the string measure after it has been determined. The only reason I can see to do it would be for the shooters determination of his POI average, not the string score.
OH and don't forget what a lot of the average shooters out there today use for measuring group size...
So that's about a two and a third inch grouping....to some...
LD
So that's about a two and a third inch grouping....to some...
LD
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Yes but we are talking measuring a group size, and I'm just providing the differences that one might encounter, in real life, OR if you read an old journal. One might get the impression that a rifle was not nearly as accurate in the 18th century as a rifle in the 19th century post 1840..., when in fact a different method of measure was applied but with the same terminology. Thus the two rifles might actually be very similar in performance.
Sorta like when folks read how soldiers were to be "clean shaven" in the 18th century, but then one finds that the soldiers were required to shave twice a week..., well we might not consider that soldier on the evening before his shave to still be "clean shaven"..., but they did back then.
LD
ResearchPress
45 Cal.
An entertaining observation for a group interested in traditional muzzle loading arms...
However, the OP made no mention of competition shooting. Figure of merit is a good way of assessing group size, which is what the original question appeared to me to be asking. What you offer may be the way you do it today, others have different experience and requirements. I offered an option, not instruction, for the OP to investigate.
David
Mark Herman
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David,
You are correct, I overlooked the original question.
You are correct, I overlooked the original question.
