How do you measure groups

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AJC1

AJC1

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I spend almost every shot or every hour in the reloading room developing, and at the range testing and practicing.... data makes better decisions than swag, so group size is important data.... I measure the extreme outside and subtract a caliber from that number for center to center.... is that the most practical way....
 
Use the Range Buddy app on my phone. Snap a picture of the target. Takes just a few seconds to calibrate the image, click on on the bullet holes and it spits out all the data for you. It creates a log so you can keep track of particular loads with particular guns. There is a free version to try and the paid version

index.php


You can display more data on the image related to gun/load/range/weather too if you like.

The app is called SubMOA if you're using an iPhone.
 
mcb said:
Use the Range Buddy app on my phone. Snap a picture of the target. Takes just a few seconds to calibrate the image, click on on the bullet holes and it spits out all the data for you. It creates a log so you can keep track of particular loads with particular guns. There is a free version to try and the paid version

index.php


You can display more data on the image related to gun/load/range/weather too if you like.
Click to expand...

This is how I do it as well. Then when I decide on a load, the load with group size goes into my reloading log
 
Gordon's Reloading Tool is free and has a group analysis function. Gordon died not too long ago, but I think you can still download it. Similar to the Range Buddy app mentioned above. It's what I use for my rifle load development.

Edited to add: For groups where I can't see the inside edges of the holes (i.e. all shots touching) I'm too busy jumping up and down and patting myself on the back to bother measuring.
 
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I get the ol' combination OD tape and tape measure out and go furthest center to center.

If I'm feeling frisky I'll exclude shots that I either pushed or pulled, and note that measurement as well separately. Sometimes it's useful to see what the group size is in a string of 10 rounds what the tightest average is. Like say I have a group and I say to myself, " Ok, 80% (8/10) shots were 2-1/4", lets see if I can repeat that..." while all 10 might be 4-5".
 
Monday, I fired 9 rounds at the 25-yard bullesye target mounted at 100 yards. Common lot of bullets that gave three 3-leaf clover groups. Each group was under 1 inch but the composite of the 3 groups was 2-1/2". 45-70 does make nice big round holes and home cast bullets are cheap. I think I'll blame it on "old eyes" and iron sights, haven't shot the rifle for about 9 months.
 
Unless your group consist of 10 or more shots, I don't think it really matters.
 
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