How do you measure your groups ??

[lotech]

I experimented with this a number of years ago but don't have my notes handy at the moment. What I recall...

I measured the actual diameter of bullet holes in paper targets. I tried copy paper that I use for most targets but also tried one weight of commercial target paper. .30 caliber holes were all less than .308" in diameter, measurably less, but I don't remember the numbers. If you doubt this, try measuring single bullet holes to verify my findings. The discrepancy causes an automatic error, especially for those who use a caliper to measure groups sizes.

Most, if not all caliper measurments of a group size are not repeatable. The readings will almost always be different. Even if the measurements were repeatable, is this amount of precision necessary for anything but benchrest or similar competition? Many like to post a photo of one caliper-measured very small group which means little without posting the two immediate five-shot groups that proceeded the very small group followed by photos of the two immediate five-shot groups that were fired following the very small group. That would provide far more information both to the shooter and the reader.

Internet users bought up all of the "all day long" rifles long before I could buy mine. I've had some accurate rifles in the last fifty years including three benchrest guns but none were "all day long" rifles.

I've found a ruler graduated in tenths and twentieths of an inch is the most useful instrument for measuring group sizes. Measurements are 100% repeatable. With regard to the number of shots in a group, I did a bunch of group shooting with eight rifles, all hunting rifles as I recall. I found three-shot groups to be meaningful if I fired eight groups. Five-shot groups were useful with five groups. Four-shot groups, six of them.

 

[powderbrake]

I use On Target software. ontargetshooting.com

 

[ebb]

I've got an elk rifle that I've owned since the 1980s and I've never reloaded for it but back then I didn't know how. I shot federal premium ammo and it would shoot less than an inch. I tried many different ammos and practiced extensively before my elk hunt, I had never seen an elk in my life. I eventually killed a 4x4 in the fall of 1989. When we field dressed it I was amassed at the size of the vital area. It was as big as a beach ball. A rifle that shot a 5 inch 100yard group would have still been adequate to kill my elk. Sometimes the size of the group is not near as important as we think we need, at least for hunting.

 

[lotech]

I've got an elk rifle that I've owned since the 1980s and I've never reloaded for it but back then I didn't know how. I shot federal premium ammo and it would shoot less than an inch. I tried many different ammos and practiced extensively before my elk hunt, I had never seen an elk in my life. I eventually killed a 4x4 in the fall of 1989. When we field dressed it I was amassed at the size of the vital area. It was as big as a beach ball. A rifle that shot a 5 inch 100yard group would have still been adequate to kill my elk. Sometimes the size of the group is not near as important as we think we need, at least for hunting.

You're right - no one "needs" incredible accuracy, especially for hunting at short distances. However, exceptional accuracy, at least for some, instills and reinforces confidence in ammo and equipment. Still necessary to practice shooting skills, as you mention. I haven't used factory ammo on a hunt since 1972; I'm quite satisfied with my own accurate handloads, but I'm sure there are good factory loads as well.

 

[Larryh128]

Measuring a group in a target . What is the right way ? I measure a single hole in the target . Shooting a 6mm ( .243) and the hole masured .226 in the target . Then I measure the group say .274 and subtract .226 that gives me .048 group . Do you use the size hole in the paper or the size of the bullet ?
If the group is .274 and I take 243 from it then my group would be .031 not .048 . But that is not the way I do it .

A piece of cardboard behind the paper target makes life easier. Also I print target on actual paper card stock which is really nice. Holes are really close to real diameter.

As to actual measuring the guys here in the old shotgun ares usually used a 25 ft Stanley tape. LOl

 

[Eagle Six]

Regardless of what method is used, if you are using vision, there is going to be a judgement call.

 

[TaperPin]

Usually there is space between bullet holes so I’ll measure inside one hole to outside the other on the far side - no math needed.

I‘m not going to complain if tighter groups eventually force a change in technique.

 

[Greg@wfcustom]

Measuring a group in a target . What is the right way ? I measure a single hole in the target . Shooting a 6mm ( .243) and the hole masured .226 in the target . Then I measure the group say .274 and subtract .226 that gives me .048 group . Do you use the size hole in the paper or the size of the bullet ?
If the group is .274 and I take 243 from it then my group would be .031 not .048 . But that is not the way I do it .

Same way I do it at matches.
With an "official" reticle device that loops the bullet holes with the correct caliber reticle.
The trick comes when measuring "one hole" groups, that takes a bit of experience to properly loop the "arc".
Luckily I've been doing it for 20+ years and have gotten fairly good at it.
That said, it is still an inexact science.
G

 

[AlNyhus]

When you measure a single hole in the paper (to the outside edge of the black smudge), that becomes the 'standard' for subtracting for your group size. The hole diameter will vary due to target paper, backing material, the gap between those and even the temp/humidity of that day. On this target that day, a single .243 bullet diameter hole measured .220. That's what was used as the deduction standard.

Using .243 as a deduction diameter would have made the group measure .102.....which it clearly is not.

Good shootin' -Al

 

[M-61]

00001

That’s one ten thousandths of an inch.
Fortunately I’ve never had a group decided by that.

 

[NorCalMikie]

If I can cover my 5 shot group with a dime, (I usually can) I'am good to go.

 

[M-61]

I always feel Gale McMillan’s .009 still is the record due to measuring and the handling of his target. Lot of questions regarding it.
Of course the .007 is fabulous.

 

[M-61]

I did enjoy measuring this.

 

[Dave Way]

I did enjoy measuring this.

What did you get? I assumed 6mm at 100 and it appeared I could see the outside edges of at least 5 bullets.

Dave.

 

[M-61]

It is 5 at 100 yards
30 BR
I like to think it’s in the 2’s
What do you get since it’s a 30 not a 6mm, or doesn’t it change?
Thanks

 

[Dave Way]

It is 5 at 100 yards
30 BR
I like to think it’s in the 2’s
What do you get since it’s a 30 not a 6mm, or doesn’t it change?
Thanks

Theoretically it should be the same since we are measuring center to center. It came out almost exactly the same at .233” versus .236” using a 6mm bullet.



Dave.

 

[dgeesaman]

Measuring a group in a target . What is the right way ? I measure a single hole in the target . Shooting a 6mm ( .243) and the hole masured .226 in the target . Then I measure the group say .274 and subtract .226 that gives me .048 group . Do you use the size hole in the paper or the size of the bullet ?
If the group is .274 and I take 243 from it then my group would be .031 not .048 . But that is not the way I do it .

This is the best way because the visible mark from the bullet may not be exactly the bullet nominal diameter.

Ballistic-X works well too.

David

 

[Bill Norris]

A piece of cardboard behind the paper target makes life easier. Also I print target on actual paper card stock which is really nice. Holes are really close to real diameter.

As to actual measuring the guys here in the old shotgun ares usually used a 25 ft Stanley tape. LOl

I found with using a good tight backer with card stock printed targets the bullet hole will be close as well.

 

[Coonman300]

I measured the hole in the target and come up with this . But a couple people said I should have used .243 . So I was wanting to know how most people measure . Is why I posted this . And thanks for all the replies .

Wow…what a group. If I shot this I’d tell everybody I shot a 1 hole group and they could kiss my ass! Great shooting!

 

[Silo1616]

Theoretically it should be the same since we are measuring center to center. It came out almost exactly the same at .233” versus .236” using a 6mm bullet.

View attachment 1489361

Dave.

How fast is the Ballistic-X process? Do you take a photo with your phone or is a scanner needed?

Wondering if it is an option for scoring our club matches.