Whats the CORRECT way to measure groups?

[Tactical30]

I keep hearing guys measuring their groups different ways, I mean there can only be 1 way thats the right way.

The way I always measured was from the outside edge of the bullet hole from the farthest hole out. I have done it that way for years.
I see some guys at the range measuring from the center of the hole and saying "This is the right way to do it." Also most of them discard the flyer shot and they say "That one dont count."
I always laugh when I hear that one. I have always measured every one and never said "oh, that one dont count!"

So what is the RIGHT way to measure groups?

 

[ChadTRG42]

Re: Whats the CORRECT way to measure groups?

Basically- center to center.
Measure the outside to outside, then subtract bullet diameter.
So, if you have a group shot by a 308 Win that is .6" outside to outside, your group is a .292" group.

 

[macman2564]

Re: Whats the CORRECT way to measure groups?

I don't know if it is the RIGHT way but for paper targets I always measure the entire diameter of the group at its furthest point and subtract the diameter of the bullets I was firing.

 

[macman2564]

Re: Whats the CORRECT way to measure groups?

Ooops beat me to it. Damned slow internet!!

 

[sobrbiker883]

Re: Whats the CORRECT way to measure groups?

I really like the "on target" software program.

On Target Software

 

[Numn]

Re: Whats the CORRECT way to measure groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">I really like the "on target" software program.

On Target Software </div></div>

+1

 

[kombayotch]

Re: Whats the CORRECT way to measure groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">Basically- center to center.
Measure the outside to outside, then subtract bullet diameter.
So, if you have a group shot by a 308 Win that is .6" outside to outside, your group is a .292" group. </div></div>

Too much work...

With a digital caliper; just zero it over a bullet and then measure outside-to-outside. Bullet diameter is already subtracted out for you. No math required.

 

[biglou13]

Re: Whats the CORRECT way to measure groups?

kom nice technique

there is slight error in the others manual technique

the hole made by bullet in paper or whatever you are shooting at usually never measures .308

paper ive been using meaures .271 bullet hole


so given a .500 outside to outside group minus .271 = .229 shot group

kom's technique zeros for the bullet hole in given paper. i'll have to stop doing math on targets.

thanks

 

[el gordo2]

Re: Whats the CORRECT way to measure groups?

I find that that measuring total width of a group and subtracting a bullet diameter isnt exactly correct since the holes are usually smaller than the bullet.It will measuresmaller than it actually is.

To find the center of any two distances you measure from the nearest edge (inside)of one thing to the farthest edge (outside) of the other. This will give you a true CTC regardless of the size of the holes.

Ontarget is what I have been using as of late. It's quite simple to use and being digital you can save your targets as files.

As to so called "flyers"?? well you have to count every shot that was fired, sometimes it's spoils a great group but such as life.

 

[Rob01]

Re: Whats the CORRECT way to measure groups?

Groups? What are they?

 

[flyboy]

Re: Whats the CORRECT way to measure groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">I really like the "on target" software program.

On Target Software </div></div>

I can't get the program to calebrate correctly to my picturs of targes. Any Ideas.

 

[sobrbiker883]

Re: Whats the CORRECT way to measure groups?

You need a reference in the picture of a known dimension, then click on the "set reference" button. Left click and hold down while you drag to other end of known distance. When you release the left click it'll popup a box for you to enter the specified distance into. I usually set my calipers to 4" or 6" and lay them on the target when I take a snapshot of it and use that for a solid reference.

 

[flyboy]

Re: Whats the CORRECT way to measure groups?

That will work. Thanks.

 

[grunteled]

Re: Whats the CORRECT way to measure groups?

How I measure depends on what I am trying to measure. If I am looking at my own overall ability then I measure every shot even if I yanked the trigger and know it.

If I am doing load development and trying to measure the rifle's ability then if I know I pulled that shot then I don't count it. Why would I? It was certainly not the ammo or rifle at fault there.

 

[bdh308]

Re: Whats the CORRECT way to measure groups?

Furthest point to furthest point or edge to edge subtracted by whatever caliber gives you group size. Example: You measure a shot group with your calipers or ruler and its .750. It would be

.750 -.308 = .442 @ 100yds.

Use cardboard behind your paper target to get more uniformed bullet holes.

My opinion...quit shooting groups and either shoot practical tactical targets or steel. It will make you a better shooter not group sizes.

 

[hiddenmongoose]

Re: Whats the CORRECT way to measure groups?

I was always taught to measure outside to outside minus bullet dia.
i only shoot groups to check zero or working a new drop chart for new bullets every 50m interval. i prefer to shoot gongs and reactive targets or varmint size targets out to 1k, i get more of a kick out of that.

 

[Greg Langelius *]

Re: Whats the CORRECT way to measure groups?

My approach is a little different (what else...?)

I lay a ruler across the centers of the two most distant holes. I measure from the outmost edge of one to the inmost edge of the other. This takes into account bullet diameters, ragged edges, etc.

Greg

 

[cavemanmoore]

Re: Whats the CORRECT way to measure groups?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">My approach is a little different (what else...?)

I lay a ruler across the centers of the two most distant holes. I measure from the outmost edge of one to the inmost edge of the other. This takes into account bullet diameters, ragged edges, etc.

Greg

</div></div>

That's too easy! Can't believe I never thought of that. Thanks Greg.

-Chris