chains1240
Member
When measuring group size do you measure from center to center or from edge to edge? Thank you.
Measuring group size
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CoRoMo
Member
Either way is fine, but it can be hard to find the exact center of a hole sometimes.
I measure with a digital caliper. If you're shooting lead bullets they'll leave a ring around the hole. Measure outside edge to outside edge and subtract bullet diameter.
If posting the group to any forum:
Subtract 1/2" and multiply range by 2.
If posting the group to any forum:
Subtract 1/2" and multiply range by 2.
CoRoMo
Member
If posting the group to any forum:
Subtract 1/2" and multiply range by 2.
And remember to use the phrase, "All day long".
chains1240
Member
Well that means that I managed to shoot a 1.05 group at 100 yards today using a rifle rest. Borrowed one to make sure the scope was sighted in. Unfortunately we still have a bit of wind. So that means using Remington Core-Lokt 150 grain I shot ".55 inches at 200 yards all day long."
CoRoMo
Member
Now you've got the hang of it!!
Seriously though, if you just happen to shoot 1.05" today, your rifle is a shooter. It can undoubtedly do sub-1" groups all day long, with the right ammo. You might not be able to do it all day long, but it sounds like the gun can. If I were you, I'd pick up different types/brands of ammo and see what your rifle 'likes' most.
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R.W.Dale
Member
If your group is made up of separate well defined bullet holes you can skip the math by simply measuring the distance between the same edge of the two farthest apart holes.
and that you can cover your groups with XXX currency ( usually a dime simply because it's smallest)
mention must also be made of the "if I do my part" angle. Which loosely translates to (if I get really really lucky my rifle might miss the same way three times again)
And remember to use the phrase, "All day long".
and that you can cover your groups with XXX currency ( usually a dime simply because it's smallest)
mention must also be made of the "if I do my part" angle. Which loosely translates to (if I get really really lucky my rifle might miss the same way three times again)
Maverick223
Member
I have found the simplest way to measure groups is to measure from the inside edge (close edge) of bullet hole No. 1 to the outside edge (far edge) of Bullet hole No. 2, that way you don't have to guess the center or subtract the caliber.
I don't subtract the Caliber. I subtract the size of the hole the bullet makes in the paper.
.308s don't make .308 holes. Hole size depends on several factors including target & backer material.
Leading edge to leading edge works great If you are lucky enough not to have you bullet holes overlapping all day long at 200yds after doing your part.
.308s don't make .308 holes. Hole size depends on several factors including target & backer material.
Leading edge to leading edge works great If you are lucky enough not to have you bullet holes overlapping all day long at 200yds after doing your part.
WNTFW said:
Finally, someone tells it like it is ... well done WNTFW!! These days I use OnTarget to measure ALL my groups since it's easy to center the circle for each shot over the bullet hole. When I check the accuracy of OnTarget using a ruler I use krochus's method since it accounts for the actual size of the hole left in the paper rather than the theoretical size.
Maverick223
Member
Yep, if you make a ragged hole, the system I detailed above won't work...you have to measure the hole and subtract...or just use OnTarget and be done with it.
Jaybird78
Member
If posting the group to any forum:
Subtract 1/2" and multiply range by 2. And remember to use the phrase, "All day long".
^^^^^^^^^^^
I about spit my soda pop all over my computer screen. This is a good one. Thanks for keeping it "real".
Subtract 1/2" and multiply range by 2.
And remember to use the phrase, "All day long".^^^^^^^^^^^
I about spit my soda pop all over my computer screen. This is a good one. Thanks for keeping it "real".
Dr T
Member
I do center to center on the extreme spread. I use a digital caliper and use the measurement "arm" to bisect the bullet hole. It gets me close enough.
Note on reporting group size: After subtracting 0.5", doubling the range, and saying "all day long", remember to note that you shot the group offhand.
Note on reporting group size: After subtracting 0.5", doubling the range, and saying "all day long", remember to note that you shot the group offhand.
Here's a good example of the holes in the target not being the same diameter as the bullet. The holes below were made by .458 bullets (.45-70) at 100 yards in a target printed on some thick card stock. The dotted grid is 1/4" and the bullet holes (dark ring) measure under 0.375". Shot #2 of the left group makes this easy to see. Measuring inside edge to outside edge would be the best way to obtain an accurate group size on this target. That's the point, the "best" way to accurately measure a group may not be the same for different calibers, ranges or target material. I've found that OnTarget provides excellent accuracy IF the scale is entered correctly. I try to pick the longest known distance on my targets as possible to minimize error when inputting the scale.
Here is a free program for your computer. I use it all the time.
http://www.ontargetshooting.com/
http://www.ontargetshooting.com/
chains1240
Member
I have purchased 150 grain NBT and 165 Sierra GK. I just wanted to see how well the rifle would shoot the green box stuff. When the wind dies down I am going to shoot the first two mentioned with the rest I borrowed. I figure if I can hit a 3" group at 200 yards that should be good enough for a deer rifle. But 3" off of bags not with the super sweet rest. When I am hunting I can use the blind window sill as a rest.
dubbleA
Member
Doing that, you will always wind up with a smaller measurement than it actually is.
Pretty simple to find the center between 2 objects is by measuring the outermost edge of one thing with the inner most edge of the other. It doesnt matter if it's 2 bullet holes in paper, a beach ball and shoe on the floor, a house an a basket ball court, two cars in a parking lot, 2 bolts in manifold and on and on
dubbleA
Member
Just for giggles, I took this 10 shot group fired at 100 yards with a AR in 5.56 and measured it to the best of my abilities using the" subtract one bullet method" and the other using the "ontarget program".
Your results might vary.........
Your results might vary.........
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