How does one properly measure a "group"? You know, you've just shot a great group and you want to tell your buds how you shot.
shooting a good group
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Sorry McGunner, you're dealing with a real Klutz. Could you please eloborate on measuring the group.
Measure the distance from the two furthest holes. Measure from the center of one hole to the center of the other hole.
Or to be very accurate, measure from the outside of each hole and subtract the diameter of the bullet.
In some cases if I call a bad shot before I scope it, I won't consider that shot in the group. So I call this a 1 1/2 inch group.
Or to be very accurate, measure from the outside of each hole and subtract the diameter of the bullet.
In some cases if I call a bad shot before I scope it, I won't consider that shot in the group. So I call this a 1 1/2 inch group.
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Another picture for illustration purposes:
The outer edges of the most distant holes are 4.51 inches apart. Subtract the diameter of the bullet (.429" for .44 Magnum) and you get a center-to-center group of 4.081"
The outer edges of the most distant holes are 4.51 inches apart. Subtract the diameter of the bullet (.429" for .44 Magnum) and you get a center-to-center group of 4.081"
You know, I've often wondered about the problem of group measurement. And I do use the method above for it's simplicity. Looking at M2's second target, there's a flyer from shooter error, but there's another that fell a bit low from the group which is used in the measurement. More importantly, there are 5 shots that are within about 1" each other. I've often wondered if it would be better to view the measurement as a center of mass problem. Set up an x-y axis on the target, measure the coordinates of each shot and calculate the "center of mass" of the group (set the mass of each hole to 1 for the calculation). Then measure the distance from the center of mass of each shot. Take the average of the distances for a "tightness" measurement of the group. The tighter the group the smaller the number and flyer or two won't have as large an impact.
Just a thought
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Just a thought
.Total group size is measured from center to center of the two most widely spaced shots with a ruler or caliper. As a practical matter it is easier to take your measurements from the inside of one hole to the outside of the other. If you are just gauging the inherent accuracy of the gun itself, the best three or four of a five-shot group are a closer picture of its true accuracy potential. For example, many new auto pistols exhibit a "4+1 syndrome" wherein the first hand chambered shot goes wide of the group and the other four shots are tightly clustered together. Some revolvers may have one or more individual chambers that shoot a little wide of the rest of the group. If you are gauging your own shooting skill, you need to consider the group size/dispersion as a whole.
I typically will shoot a 10 round group and drop two of them (explained below). I feel ten rounds gives a better representation of my skill rather than just being lucky. The remaining 8 out of 10 I measure center to center. I usually will take a photo with something that is a common size so others can relate just by seeing it. I also write the key info on the target before the photo to help me remember later. To me, this method lets me determine that 80% of my shots will fall within this distance at this range. I think the picture says it all. I don't think there is any right or wrong way to do it. This is just what I've come up with.
Shooting groups
Most everyone is giving good info. The big variable is to realise some days we just don't shoot as well as others. On some days I can shoot real tight groups with my Glock 17L long slide, but on a bad day,and we all have them, I can't hit the side of a barn from the inside! Judge your shooting according to your overall average . Don't get discouraged .
Most everyone is giving good info. The big variable is to realise some days we just don't shoot as well as others. On some days I can shoot real tight groups with my Glock 17L long slide, but on a bad day,and we all have them, I can't hit the side of a barn from the inside! Judge your shooting according to your overall average . Don't get discouraged .
A friend of mine shot the collegiate pistol nationals at Benning in March. They used electronic targets, and not only would the monitor next to the shooter display each shot, but would calculate and display the mean point of impact as well.
Depending on what information you are trying to collect there is a little more to it than just measuring the shot spread.
This is about a 3/4 inch five shot group. I started out to shoot five shot groups.
Then I shot the two remain rounds in the magazine. Since those two rounds bridged the gap between the first five shots, the group size wasn't changed.
I don't know, is the second group better than the first group?
It sure feels a lot better.
Now on this target the group size is larger but not a lot larger, if the shooter caused flyer is discounted. But the shooter is responsible for every shot, so the flyer should be counted. Don't you think? Which then makes the third group terrible compared to the first two.
Personally, as I recall, I just blew the shot, so I count it in the group and try to do better the next time.
This is about a 3/4 inch five shot group. I started out to shoot five shot groups.
Then I shot the two remain rounds in the magazine. Since those two rounds bridged the gap between the first five shots, the group size wasn't changed.
I don't know, is the second group better than the first group?
It sure feels a lot better.
Now on this target the group size is larger but not a lot larger, if the shooter caused flyer is discounted. But the shooter is responsible for every shot, so the flyer should be counted. Don't you think? Which then makes the third group terrible compared to the first two.
Personally, as I recall, I just blew the shot, so I count it in the group and try to do better the next time.
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