Measuring Groups

[gilream]

To measure groups accurately I have always measured the diameter of a single bullet hole in my target and used this number as the base diameter to subtract from the widest edge of a cluster of holes in the target. This single bullet hole is of course always smaller than bullet diameter due to the shrinking aspect of the paper.

Do sanctioned bench rest matches use the same technique? Or do they simply subtract the known bullet diameter from all groups across the board?

Thanks...Mike

 

[BT1]

To measure groups accurately I have always measured the diameter of a single bullet hole in my target and used this number as the base diameter to subtract from the widest edge of a cluster of holes in the target. This single bullet hole is of course always smaller than bullet diameter due to the shrinking aspect of the paper.

Do sanctioned bench rest matches use the same technique? Or do they simply subtract the known bullet diameter from all groups across the board?

Thanks...Mike

This is the tool I was advised to buy. Has not arrived, but looks like it will do the job. Steve

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

 

[Mozella]

If you have a scanner, get a copy of On Target software and use it to mark and measure your shots. It works great, is very accurate, and produces data which you can sort and examine using a spread sheet. So not only do you know all about your shots, you have something you can study and understand including Mean Radius (also known as average to center). It's a real pain to calculate manually, but On Target does it automatically. It is much more meaningful than group size or group MOA.
If you don't have a scanner, you can use your smart phone camera. It works as well but takes an extra few seconds to calibrate the target size.

 

[aj300mag]

Do sanctioned bench rest matches use the same technique? Or do they simply subtract the known bullet diameter from all groups across the board?

Thanks...Mike

No. Shortrange Benchrest uses dial calipers with the attachment BT1 refers to.

 

[BT1]

If you have a scanner, get a copy of On Target software and use it to mark and measure your shots. It works great, is very accurate, and produces data which you can sort and examine using a spread sheet. So not only do you know all about your shots, you have something you can study and understand including Mean Radius (also known as average to center). It's a real pain to calculate manually, but On Target does it automatically. It is much more meaningful than group size or group MOA.
If you don't have a scanner, you can use your smart phone camera. It works as well but takes an extra few seconds to calibrate the target size.

Just tried the software. I have seen it before, but never tried. Seems easy to use. As Mike asked, is there anyone holding IBS matches using this? It would seem hard to accomplish at a match site, with a large number of targets to scan. Begs the question, is there a sre Ise n

No. Shortrange Benchrest uses dial calipers with the attachment BT1 refers to.

I'll try to write up a short report on how easy or hard the Neil Jones attachment works from a first user perspective. Steve

 

[Joe Salt]

I don't have a picture of the one we have at our club but I know it has a circle with a dot in the center. We measure center to center for 1000 yards.

Joe Salt

 

[aj300mag]

Just tried the software. I have seen it before, but never tried. Seems easy to use. As Mike asked, is there anyone holding IBS matches using this? It would seem hard to accomplish at a match site, with a large number of targets to scan. Begs the question, is there a sre Ise n

I'll try to write up a short report on how easy or hard the Neil Jones attachment works from a first user perspective. Steve

Steve you'll find that if five different people measure with it you'll get five different measurements. Generally the bullet hole in the paper is smaller than the diameter engraved into the template so it's up to the users descretion as to centering the template over the holes. You'll have an advantage if you have experience using an optical comparator.

I've made my own template to include 6.5mm, 7mm and .338.

 

[BT1]

Following up with a report on the Neil Jones group measurement system. Arrived today packaged well despite the USPS using it for a football, everything came thru OK. Instructions left a bit for the imagination, but the actual picture on the web site was more informative. Used just a generic digital calipers for this test. Did not want to f--k up my Mitutoyo for this test. Will be fine for local matches. Any possible record targets go directly to the IBS anyway.

Mounting the 2 components that actually do the measurements took all of a few minutes.
Reading the instructions and actually measuring a 5 shot group in 6mm, was very quick and intuitive.
Measured the same group 3 times and right! Every time came up with a different value. 1.454, 1.461 and 1.449. I bet if I would keep doing it maybe 1 out of 10 try's would give the exact same reading. I thought the 3x magnifier was awkward to use sitting down. If standing less of a problem. With and without the 3x magnifier, same issue with different results. Most likely will not use it. Makes the tool harder to manipulate and store.

Conclusion, yes I would buy again, maybe without the magnifier. If nothing else it gives a little bit more credibility to the scores at a match rather than methods we typically used. Steve