Measuring groups

[Joe Salt]

Listen this is real easy, In 1000 yard Competition if you shoot a record the target has to be measured by six people on the board of directors of the club then averaged. We Measure with calipers with magnifiers with cross hairs and we measure center to center of the two furthest shots. But like I said before when you get something at a hundred yards that is tight, measure to the outside edge and subtract the diameter of the bullet. Keep it simple.
Oh and when we measure closes to center we take a ruler and put a cross in the X then measure from the center of the X to the center of the bullet hole. So whatever you think you have, measure at least 6 times then average.

Joe Salt

 

[Erik Cortina]

Listen this is real easy, In 1000 yard Competition if you shoot a record the target has to be measured by six people on the board of directors of the club then averaged. We Measure with calipers with magnifiers with cross hairs and we measure center to center of the two furthest shots. But like I said before when you get something at a hundred yards that is tight, measure to the outside edge and subtract the diameter of the bullet. Keep it simple.
Oh and when we measure closes to center we take a ruler and put a cross in the X then measure from the center of the X to the center of the bullet hole. So whatever you think you have, measure at least 6 times then average.

Joe Salt

Joe, the issue I believe with subtracting bullet diameter is that bullets don't punch holes of same diameter as the bullets, so that would induce error into the measurement.

 

[aj300mag]

Erik I've seen 6mm holes so tight you'd have thought they were shot it a .22 ...

 

[Erik Cortina]

Erik I've seen 6mm holes so tight you'd have thought they were shot it a .22 ...

Me too, but I've also seen them bigger.

 

[Joe Salt]

Erik I don't care what size hole it makes, that is the caliber you shot. So if you measure to the outside and subtract caliber that is your group! Go ask some of the 100 yard shooters that do the measuring what they do.

Joe Salt

 

[Erik Cortina]

Erik I don't care what size hole it makes, that is the caliber you shot. So if you measure to the outside and subtract caliber that is your group! Go ask some of the 100 yard shooters that do the measuring what they do.

Joe Salt

Ok, relax!

I'm asking simply because I'm curious how it's done. What you say makes sense, but I'm wondering what the group measuring protocol is.

 

[Joe Salt]

Eric here is something to read!http://internationalbenchrest.com/downloads/IBS_Rule_Book_12b_Revised_2012.pdf

Joe Salt

 

[butchlambert]

This is a cheap measuring tool.
http://www.sinclairintl.com/reloading-equipment/measuring-tools/calipers/sinclair-group-measuring-caliper-attachment-prod38778.aspx
This is the commonly used tool to measure groups.
http://bulletin.accurateshooter.com/2014/08/measure-groups-precisely-with-neil-jones-tool/

 

[Uthink Uknow]

As I see it, and that would be in bifocals, most of this is flawed unless you are using a moving backer system. What's to say that the group is a three, four, or five shot group is the first two were tight and the shooter didn't shoot all the shots? I have the reticle attachment to screw onto calipers and the pinned block that locks throught the target and doesn't move while adjusting out for the measurement.
The idea to place a ruler next to the group for measuring on the Internet is flawed unless the ruler is clear so I can see the ruler isn't hiding the errant shot.
Somewhere I saw someone is holding an Internet group "match". Most or all arguments would be taken care of if it was a score match and the targets were sent to a central scorer. We used to have the postal matches on another website and they proved to be well attended. Over the course of a year, the contestants shot five five shot score target matches. I don't recall any abrasive comments over the Internet. I think on average there were better than 70 shooters in each of these matches. All this pales in comparison to the old postal matches that Sinclair, International used to conduct worldwide. They employed as many as three people to score the targets and handle all the mailing around the world. I don't think any wars were started over the results. But, as I said before, a score match takes care of most of the differences of opinions about results. It's supposed to be fun, right?
Ah, Butch posted of the caliper and attachment I have. The Jones.

 

[butchlambert]

As I see it, and that would be in bifocals, most of this is flawed unless you are using a moving backer system. What's to say that the group is a three, four, or five shot group is the first two were tight and the shooter didn't shoot all the shots? I have the reticle attachment to screw onto calipers and the pinned block that locks throught the target and doesn't move while adjusting out for the measurement.
The idea to place a ruler next to the group for measuring on the Internet is flawed unless the ruler is clear so I can see the ruler isn't hiding the errant shot.
Somewhere I saw someone is holding an Internet group "match". Most or all arguments would be taken care of if it was a score match and the targets were sent to a central scorer. We used to have the postal matches on another website and they proved to be well attended. Over the course of a year, the contestants shot five five shot score target matches. I don't recall any abrasive comments over the Internet. I think on average there were better than 70 shooters in each of these matches. All this pales in comparison to the old postal matches that Sinclair, International used to conduct worldwide. They employed as many as three people to score the targets and handle all the mailing around the world. I don't think any wars were started over the results. But, as I said before, a score match takes care of most of the differences of opinions about results. It's supposed to be fun, right?
Ah, Butch posted of the caliper and attachment I have. The Jones.

I had one in the old days and donated it to Francis Bike(sp) for his shooting club. Need to have a better pic for the rookies to see and understand how it works.

 

[Joe Salt]

Ok all I'm saying is the Caliber matters! they have to know what Cal. you are shooting. They make you fill out a card that has to be up to date, or they can't get the right measurement. Then it is from the outside edge.

Joe Salt

 

[aj300mag]

Erik I don't care what size hole it makes, that is the caliber you shot. So if you measure to the outside and subtract caliber that is your group! Go ask some of the 100 yard shooters that do the measuring what they do.

Joe Salt

No we don't...

I use a Neil Jones attachment on my calpiers and don't subtract anything. Been involved in running benchrest matches for over ten years, never seen targets measured using the method you've described.

 

[Joe Salt]

Uthink Unown For Score we us Caliber plugs to see if you are cutting the line. And that depends on cal. also!

Joe Salt

 

[dickn52]

Ahhh. Opinions, everyone has one it seems. I keep it simple. Outside to outside minus the bullet diameter equals center to center. I'm most likely off by 1 or 2 thousandths every now and then.

 

[aj300mag]

Uthink Unown For Score we us Caliber plugs to see if you are cutting the line. And that depends on cal. also!

Joe Salt

Scoring plugs are outdated. IBS has a scoring tool that is used to determine if the bullet hole cuts the ring...

 

[Joe Salt]

aj300mag Then why do they ask to know the cal.? We have the same measuring tool at our club it measures center to center or outside edges.

Joe Salt

 

[butchlambert]

The Neil Jones attachments has precise circles for ea caliber. It also has a magnifier. You center the appropriate holes over the shot bullet holes and take your measurement. The guy that measures needs to know the caliber that you are shooting.

 

[aj300mag]

aj300mag Then why do they ask to know the cal.? We have the same measuring tool at our club it measures center to center or outside edges.

Joe Salt

The template on the group scoring tool has different bullet diameters inscribed into it. The scorer needs to know what caliber you shot so he can use the proper circle.

Custom template I made up to include .22, 6mm, 6.5mm, 7mm & .308 .

 

[aj300mag]

Ahhh. Opinions, everyone has one it seems. I keep it simple. Outside to outside minus the bullet diameter equals center to center. I'm most likely off by 1 or 2 thousandths every now and then.

Use a digital caliper. Measure a single hole and reset the readout to zero. Measure outside to outside and you have an actual reading. Any thing else is BS...

 

[Tim Singleton]

NBRSA rule book pg 26

(13) GROUP MEASUREMENTS. Groups are to be measured by any method approved by the NBRSA in .001 inch. The Sweany Type Reticle Rule (or its equivalent) will be the only official measuring device used at all Registered Matches. In measuring groups fired with calibers larger than .22 (unless the Reticle is calibrated for the caliber to be measured) the measurement shall be made from the extreme outside edges of the 2 widest bullet holes and the actual differential of the larger calibers shall be subtracted from the measurement read on the measuring scale. (See: Target Drawing in back of Rulebook.)
Targets are to be marked in the upper right-hand margin, indicating reduction in measurement (6-mm reduction of .019 and 308 reduction of .084).


I believe the Niel Jones tool is the most commonly used at matches and is the same design as the Sweany tool which is no longer made.
http://www.neiljones.com/html/target_measuring.html

That is how group measuring is done at registered NBRSA matches