Would like opinions on how to measure this group size.

[njlondon]

I always have measured from anywhere the paper is discoloured, punctured or not.

In the sample below that is what I have done. There is more discolouration than I normally encounter with the paper I use.

This 5 shot 100 yard target was a test target from the builder.

Comments on if this is correct appreciated.

Edit: Thinking about it, it's probably a dumb question; the bullets hit and discoloured the paper so yes, you measure all the discolouration.

 

[100zero]

I measure from one ragged edge to farthest on the other side then minus the calibre diameter.

 

[njlondon]

That's what I did.

 

[yodave]

push the paper back from the back side of the target and fill in what you can from whats missing, measure the widest part of the hole from the discolored to the discolored edges and subtract the bullet diameter to get the center to center measurement.
as the bullet passes through the paper it will mark it black, with the exception of a full wad cutter which acts as the perfect gentleman's hole punch

 

[Daver_II]

I measure discolouration "outside-outside" and subtract the actual bullet impact diameter.

What I mean is fire one round on the paper aside from my group (usually into its own target as it is my confirmatory zero round), I measure that one round including the discolouration.

Then I use that as my round diameter.

- the reason being is I started using laminated targets and a .308 actually measures .294" due to the plastic healing.

Then I measure outside to outside the whole group (discolour included) and subtract the bullet diameter.

If I didn't do this, I would be cheating an extra .01 or so


Oh, and measure a few times....

 

[njlondon]

push the paper back from the back side of the target and fill in what you can from whats missing, measure the widest part of the hole from the discolored to the discolored edges and subtract the bullet diameter to get the center to center measurement.
as the bullet passes through the paper it will mark it black, with the exception of a full wad cutter which acts as the perfect gentleman's hole punch

The paper is pushed back. I measured longest distance from beginning of discolouration to end of same, less .308.
Is that is what you intending to say?
Or are you saying to measure the hole only?

 

[rifleman338]

Try laying it flat upside down on a table and push back the paper folds to the centre then put a piece of scotch tape on the back so it will stay in place.

 

[njlondon]

Try laying it flat upside down on a table and push back the paper folds to the centre then put a piece of scotch tape on the back so it will stay in place.

It's flat. That's not the question.
Do I include all discolouration or just measure the hole.

I agree with DaverII above; outside discolouration to outside discolouration, less bullet diameter.

 

[Sierra 2]

Outside discolouration to outside discolouration, less bullet diameter.

 

[Sierra 2]

View attachment 137537

 

[guntech]

I measure discolouration "outside-outside" and subtract the actual bullet impact diameter.

What I mean is fire one round on the paper aside from my group (usually into its own target as it is my confirmatory zero round), I measure that one round including the discolouration.

Then I use that as my round diameter.

This is the correct way... but you don't have a single bullet hole to measure... it doesn't really make much difference though... nothing official with this group...

 

[marcoman]

Wow. Amazing that there is so much confusion on how to measure a group. The Rimfire section is rife with mismeasured groupings.

 

[njlondon]

I have always measured properly.
I started this post only because there was so much discoloration around the actual holes.
An anomaly; I don't see that on my targets with the paper I use.
Thanks for all the replies.

 

[yodave]

the cardboard and paper will heal so to speak, the black skid mark to black skid mark less the bullet diameter is the correct method. the hole you see in the cardboard is after the healing of the paper and is not true to group size

 

[yodave]

View attachment 137537

this is the correct way to measure

 

[Sakoman .308]

That's a fine group Njlondon.

 

[legi0n]

here's how it's measured (hole circles to scale)
only marked 3 significant holes to prevent cluttering the image

 

[njlondon]

That's a fine group Njlondon.

Thank you, but it's not mine.
One of two 5 shot 100 yards test targets sent to me by the builder of a custom rifle in .308.
Both targets were the same in group size. Mid 2s by my micrometer.

 

[thenerdboy]

Wow. Amazing that there is so much confusion on how to measure a group. The Rimfire section is rife with mismeasured groupings.

What's worse over there is the number of targets shot in the bush/backyard with no proof of actual range, IMO. I remember looking at some photos a long time ago that had to have been paced out without a laser rangefinder. Many of them are gone now that Photobucket changed.