Measuring groups

[1holeaddict]

I read alot of postings about what size groups a gun will do. I often wonder if everyone is measuring group sizes correctly. Would anybody like to give a detailed explanation on measuring group sizes including what it means to shoot sub MOA at extended ranges and what it means when it is said it shoots in the .1's,.2's,.3's.

 

[bowslngr]

Measuring groups -- what I do: I measure the extreme spread from outside of one bullet hole to the outside of the other bullet hole (actually the outside of the grayish mark the bullet leave on the paper) using a caliper. Then subtract the diameter of the bullet. I have heard that this may not be completely accurate as there is some stretching of the paper that occurs when the bullet punches through it, but it is good enough for my purposes.

MOA at extended ranges: The easy and not completely accurate answer is that one MOA equals one inch at 100 yards and increases proportionately as you go further in range (2 inches at 200 yards, 3 at 300, etc). However, an MOA is actually equal to 1.047" at 100 yards. Anyway, if someone refers to MOA at extended range, they may be talking about roughly 6 inches at 600 yards, 8 at 800, 10 at 1000, or something else completely.

Shooting in the fractions: Groups that measure between 0.100 and 0.199 inches would be referred to as "in the .1s" and so on.

OK. Now somebody can shoot me full of holes.

 

[mr45man]

.1's,.2's,.3's. OK, measured with a caliper .5 would be 5 tenths of an inch or 1/2 inch
MOA is about 1 inch at 100 yards or 2 inches at 200 yards. and so forth.

Measuring , you have 2 bullet holes, using a set of calipers measure from the
the out side of one hole to the inside of the other that gives you center to center.
There that's clear as mud LOL
John H.

 

[jhord]

I think most people know what it means and how to measure it. But the BS factor that gets applied to the end result... now that needs some 'splainin. ;D

 

[1holeaddict]

I think most people know what it means and how to measure it. But the BS factor that gets applied to the end result... now that needs some 'splainin. ;D

I think ur exactly right. I love the guys who say my gun will shoot in 1 hole all day until u ask to see some targets.

 

[fr3db3ar]

I think most people know what it means and how to measure it. But the BS factor that gets applied to the end result... now that needs some 'splainin. ;D

I think ur exactly right. I love the guys who say my gun will shoot in 1 hole all day until u ask to see some targets.

Hey now......every time I shoot my gun it makes ONE hole ;D

that's the way it's supposed to work right?

 

[Mega]

Measuring , you have 2 bullet holes, using a set of calipers measure from the
the out side of one hole to the inside of the other that gives you center to center.
There that's clear as mud LOL
John H.

Fair enough at reasonable long distance but come back to say 200 yards and closer with a decent Target / Benchrest Rifle which will cluster bullet holes that overlap so it's impossible to measure the outside then the inside of the furthest in the group...eg a 6.5x47L Benchrest shooting a 0.2" group at 200 yards will just be one virtual hole so the only way to measure is the outside of the largest extremity then subtract the calibre. Somtimes it is possible to count each individual shot but usually one goes missing inside the little mess.

Take the same rifle shooting 550 yards (500m) and it becomes a whole lot easier to measure the 1.5-2" group.

Trying to develop loads at 100 yards with something like this is a waste of time as all the groups look the same. It's sight in and move target out to 200-300 yards to get any idea of which load groups the best. The downside of course is wind effect as you try tiny groups.

 

[jhord]

There's a lot of varmint rifles around that need to be taken to the Kelbly's Super Shoot. LOL. MY new 6 Dasher shot an .078" 5 shot group one day, so I guess I can say it shoots in the "0's all day long." As that's the only group it shot that day. 8)


[/quote]I think ur exactly right. I love the guys who say my gun will shoot in 1 hole all day until u ask to see some targets.
[/quote]

 

[alf]

Depending on target material, if you measure a single bullet hole, the true diameter is bigger than the black around the hole itself.

I think that titbit tends to get lost in measuring.......

 

[brennan burkett hutto]

MOA is 1inch at 100 2inches at 200 and so on and the way we measure groups is with a caliper from the center of 1 bullet hole 2 the other the extremes. Thats pretty much what everyone else said and i agree with them.
brennan "butterbean"

 

[Bulseyetom]

I try to use targets with heavy material so they leave a good hole. The Sinclair practice target has 3 rows of bulls so I can shoot quite a few groups without changing targets. Their Load Development Target has the best paper of any target material I ever saw. Holes in it look like they were cut with a paper punch. I use my electronic caliper and measure trhe diameter of one hole, then zero the caliper at that number. I then measure outside to outside of the farthest bullet holes to get the approximate group size. If it is too big, I just mis-read the caliper so that all my groups are in the 3's at the worst! Tom

 

[Witchhunter]

Make sure not to count "fliers", as they increase group size dramatically. Sometimes enough so that your groups are embarrassing even for internet standards.

 

[Dans40X]

mr45man,
.1's,.2's,.3's. OK, measured with a caliper .5 would be 5 tenths of an inch or 1/2 inch
MOA is about 1 inch at 100 yards or 2 inches at 200 yards. and so forth.

.5 would be 5 tensof an inch or 1/2 inch.

5 tenths(slang) would be .0005" of an inch or 1/2 a thousandth or 1 seventh of a head hair @ .0035".
0.0"= tens
0.00"= hundreds
0.000"= thousandth
0.0000"= ten thousandth

 

[snakepit]

You might check the "On Target Precision Calculator Program". This is a very easy method of measuring your groups etc on your computer. It gives you a lot of information about your measurements and you can store everything on your computer. There is a lot that can be done with this program. You can try it out with a free 15 day trial. When I purchased it the cost was a one time fee of $11.99. Works good for me.

www.ontargetshooting.com

 

[Jeff A]

You might check the "On Target Precision Calculator Program". This is a very easy method of measuring your groups etc on your computer. It gives you a lot of information about your measurements and you can store everything on your computer. There is a lot that can be done with this program. You can try it out with a free 15 day trial. When I purchased it the cost was a one time fee of $11.99. Works good for me.

www.ontargetshooting.com

I use calipers most of the time but when I want to be precise or email bragging rights, I too use the OnTarget program.

 

[BoydAllen]

I find the mention of measuring groups shot at 1-200 yd. being a waste of time amusing, since there is an entire sport that is all about those measurements. The most accurate measurements of small groups, at matches, is done by experienced scorers that use (for group) tools that work like the one that Neil Jones sells. http://www.neiljones.com/html/target_measuring.html
I have one, and take comfort that my measurements with bare calipers are generally larger than with it, by a small margin. With the caliper I measure to the outside of the black mark, and subtract the diameter to the same place, of a single bullet hole in the same target paper.

 

[Area Man]

I measure outside edge of bullet hole to outside edge of bullet hole, then subtract the bullet diameter to get the actual group size.

Then divide by 1/2 to get the internet group size. All day long.

 

[johara1]

Like Boyd said when your at a match and somebody else does the measuring is the best gage, but i saw that flawed when the scoring persons buddy is close to the win. a simple rule is with the 6mm is when the "hole" measures out side .333,it looks like a .30 cal bullet hole. A good one will back it up almost every time you go out…….. jim

 

[Terry]

http://www.neiljones.com/html/target_measuring.html

This is what I use.

 

[mikecr]

I use Boyd's outside caliper method,, subtract a hole -as it cuts the paper.