Do you measure center to center, outside edge to outside edge? What is the standard way to measure a 3 shot or 5 shot group?

Thanks.

I measure mine center to center. Right wrong or otherwise.

Measure to the outside edge of the Group, subtract one caliber distance to find the "center to center" group measurement

You could also go inside edges of the two farthest apart holes, then add bullet diameter.

I usually go outside to outside, minus caliber. I use the extreme edge of the black smudge, not just the hole.

For internet use, look at it and say, by golly that's 1/2 MOA!

I dont get to picky....I just eyball center to center

quote:

Originally posted by crbutler:
For internet use, look at it and say, by golly that's 1/2 MOA!

That's it! Just measure and double the distance. If you shot a 2 inch group, tell everyone you were shooting at 400 yards.
Your friends are guaranteed to be impressed.

quote:

Originally posted by ted thorn:
I dont get to picky....I just eyball center to center

+1

Can't be more than about .025" off.

quote:

Originally posted by rcamuglia:
Measure to the outside edge of the Group, subtract one caliber distance to find the "center to center" group measurement

+1

With really tight groups such as this one it is the only way to measure it.

While in cyberspace a "group", like a measurement, can be whatever you want it to be. However, 3 shots are not really a group. It's merely a indication of a POI.
I'm sure we will next be hearing about "groups" that are only two shots. The logic of course being that you seldom shoot at an animal more that twice.
Does that mean I can start quoting one shot "groups"?

Make a one shot group and distract the calibers diameter from the outside -outside meassurement...

That´s how the hunting magazine editor´s probably do...

(just a joke)

Very simple.

Go here and get the free download.

http://www.ontargetshooting.com/


Barstooler

quote:

Originally posted by wasbeeman:
However, 3 shots are not really a group. It's merely a indication of a POI.

quote:

How to do you measure groups?

with a ruler? tee hee roger

quote:

Originally posted by dogcat:
Do you measure center to center, outside edge to outside edge? What is the standard way to measure a 3 shot or 5 shot group?

Thanks.

Find greatest dimension of group; measure from outside of one "furthest" hole to the inside of the other "furthest" for center-to-center size. No math needed. (I'm mathematically challenged.)

Use one of these:

Use one or a bunch of these, as necessary

As long as I can cover my group(s)

all is right with the world

GWB

a quarter is 0.955 inches and a good field measuring device if needed.

quote:

Originally posted by rcamuglia:
Measure to the outside edge of the Group, subtract one caliber distance to find the "center to center" group measurement

You got it rc!

I get lucky once in a while.

Fire one shot and miss with the others

quote:

Originally posted by crbutler:
For internet use, look at it and say, by golly that's 1/2 MOA!

lmao

quote:

Originally posted by rcamuglia:
I get lucky once in a while.

rc, since that post was right after my post and knowing your propensity for , it would be possible for me to assume you're referring to my groups as "lucky". You're right! Actually more a function of statistics than anything else. You do enough shooting and statistics will say that eventually you will get a .2" group out of even a 2" shooter. IOW all the shots in the groups "miss" towards the center of the group.

Those targets were from a few years ago and I don't shoot at 100 yards anymore, too BORING and, shall I say, unchallenging. I'm sure even you might have a couple of targets in the 2's if you weren't so busy pounding steel at long range.

BTW those were just the targets that had written on them the calculation of the group size showing the method under discussion. I could fill a couple of pages of one holers if it were just the group itself under discussion. Again BORING!

No good, woods. They all missed the centre!

I was going to post a pic of one of my better groups but now I won't.

I have a mate or two who measure the accuracy of their guns by firing a 'group' until two shots nearly touch and then that's the accuracy! And no, I don't say a thing - well, other than "Wow, that's good , hey?"

GWB, dont post pictures before you actually get one in the cap.

Since I am the weakest link in shooting great groups, I shoot 4 shots, and measure the best three.

quote:

Originally posted by wasbeeman:
While in cyberspace a "group", like a measurement, can be whatever you want it to be. However, 3 shots are not really a group. It's merely a indication of a POI.
I'm sure we will next be hearing about "groups" that are only two shots. The logic of course being that you seldom shoot at an animal more that twice.
Does that mean I can start quoting one shot "groups"?

I feel the same. It's amazing how groups can grow in size from 2 additional shots.

seems like lately i find a yardstick useful

quote:

Originally posted by woods:

quote:

Originally posted by rcamuglia:
I get lucky once in a while.

rc, since that post was right after my post and knowing your propensity for , it would be possible for me to assume you're referring to my groups as "lucky".

You're too sensitive!

I was not talking about those beautiful ragged holes, but the fact that sometimes I actually know the answer to something!

quote:

I think that's called an alternative group. You know, a group that refuses to be together.

I get lots of alternative groups, I either do five or six 3 shot groups and measure outside to outside minus calibre and work out the average of the five or six, or if I don't want to waste too many shots I do one 5 shot group measure the 5 and the best 3 and take the average. You get remarkably similar numbers, even though I don't think there is any logical mathematical or scientific basis behind this.

I measure center to center as the center of the hole actually represents the real POI of the bullet.

If you measure outside to outside, then subtract one full bullet diameter, you will actually end up with a number which is likely slightly smaller than your actual group.

Why? Because most bullets do not make a hole the same as their full diameter. Bullets of .308" diameter for instance make holes which are often more like .300" in diameter or even smaller. That depends, of course, on the paper itself, the humidity, etc.

A parallel way to envision this is to imagine shooting through a sheet of rubber. The rubber stretches until the bullet finally "pops" through, then the rubber contracts and leaves a much smaller hole than the full bullet diameter.

The same thing usually happens when a bullet is shot through paper, though not nearly to the same degree.

As the stretch and contraction of paper is not as much as happens with rubber, the bullet hole may not be "much" smaller, but it usually IS smaller enough to easily measure with a dial caliper.

A more precise way is to measure the farthest apart holes outside to outside, then measure one bullet hole and subtract the diameter of that one bullet hole from the outside to outside measurement.

Boy, talk about pickin' a nit.

quote:

Originally posted by dogcat:
Do you measure center to center, outside edge to outside edge? What is the standard way to measure a 3 shot or 5 shot group?

Thanks.

Center to center for consistency between calibers, some may be shooting bowling balls while others are shooting BBs.

Some shoot 3-shots and measure extreme spread, regardless which way it spreads. Others shoot 5-shots and measure lateral width by horizontal height to keep track of your groupings to better identify issues. As example, your extreme spread my be 1.5MOA, but the group may be .25MOA tall while strung out 1.5MOA wide.

There is an NRA standard for accuracy testing, and that involves an average of an aggregate of 5-shot groups. There are many ways to measure groups to judge performance, but I tend to shoot 3-shot groups only to center the POI where I wish it to be for sighting purposes. I normally shoot multiple 5-shot groups to judge rifle performance.

Best

i just "eye-ball" em'.

quote:

Originally posted by LBGuy:
i just "eye-ball" em'.

Me too

Unless you are shooting bullets of different diameters at the same target, outside to outside measures of the two furthest apart(3rd group) are the same as center to center.

Only cloverleafs are good. In that case, why measure....

If you see paper between any two bullets- it sucks.

I'll call ya' on that,
post your pix.

and raise ya this.....

for every one of those cloverleafs you can show, I bet I can show you two of my group that don't, some even as far out as 300 yds.
Best
GWB

I use a percentage system. 75% group size and 100% group size. I also look at group shape. But accuracy is the distance of the worst shot from the mean centre. That's how much allowence I need to make for a good hit.