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How do you measure your groups?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 15:14
Gil P. View Drop Down
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The way I do it is I measure the two furthest bullet holes away from each other edge to edge, and then I subtract .308 (bullet diameter) from that number to get a center to center number. I am using electronic calipers to measure my group sizes.

I am asking because, I have seen other 5 shot groups that measure .5 inches (shot with an unknown caliber) that look almost like all the bullets are going into the same hole.

So, how do you measure your groups? And, what is the standard way of measuring them? I think I might be measuring mine incorrectly.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 16:01
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Center hole to center hole is the most accurate measurement. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 16:17
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+1!

Your doing it right
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 17:29
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I generally cover them with a #2 pencil eraser.
If I can see anything outside the eraser I know I've made an error and must practice a while longer. Bandito
 
Gil your way will work fine.
Center/Center also works well.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 19:50
Gil P. View Drop Down
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Originally posted by Mike McDonald Mike McDonald wrote:



I generally cover them with a #2 pencil eraser.
If I can see anything outside the eraser I know I've made an error and must practice a while longer. Bandito
 
Gil your way will work fine.
Center/Center also works well.
If I can see anything outside the eraser I know I've made an error and must practice a while longer.

Haha very funny, but I don't think im quite there yet.

Thanks for the help guys, I suppose the one hole looking group I saw wasn't actually measured. They simply stated a guesstimated size and it was probably a lot smaller than stated.

On a side note, I sent my rifle to Phoenix Custom Rifles to have a New barrel put on, barrel channel opened, new recoil lug installed and some action truing done. I should be getting it back in a about a month (maybe less). Then, with practice I can see my groups REALLY start to shrink! Ill post pictures for you all when it gets here.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/03/2013 at 22:25
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+2 center hole to center hole.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 05:31
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Gil, Mike might of been kidding about the pencil eraser and then again he might not.... Shocked
 
Mike is really THAT good of a shooter.
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I'm pretty sure he wasn't kidding...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 15:18
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Never doubted him; I know there are some pretty darn incredible shooters out there.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 17:40
Mike McDonald View Drop Down
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seriously, here's how I measure mine;
You know how, when you are looking at the bullet holes on light colored paper, there's a black ring around the circumfernece of the hole?
I use a dial caliper and a magnifier and measure from the outside of that black ring, which theoretically is the true diameter of the bullet as it passed through the target, to the outside of what looks to be the farthest hole on the other side of the group.
Then I shift 90 degrees and measure another two holes.
If I've done my part we're measuring a single hole, looking at the outside of the radii of the group and measuring for example, east/west, then north/south.   I take the largest measurement and subtract bullet diameter for group size.
I then measure group center to the center of the target, which is the aiming point.  That's the true group measure for me;  did I actually put the pointy thingies where I was aiming?
 
For example, here's a test group I fired prone/cold bore when testing the XOTIC prototype for Chris;
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 17:42
Mike McDonald View Drop Down
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Sorry, 'puter locked up.
Anyway, you can see it's a decent group with factory ammo, 1 flyer but it happens.
It's also about .35" away from target center, whcih was the aim point, so for me, that's a 0.345 inch group.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 17:53
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Originally posted by Mike McDonald Mike McDonald wrote:

Sorry, 'puter locked up.
Anyway, you can see it's a decent group with factory ammo, 1 flyer but it happens.
It's also about .35" away from target center, whcih was the aim point, so for me, that's a 0.345 inch group.
 
FLyer!?!?!? Shocked  where?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 17:56
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Very nice! 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 18:29
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Originally posted by budperm budperm wrote:

Originally posted by Mike McDonald Mike McDonald wrote:

Sorry, 'puter locked up.
Anyway, you can see it's a decent group with factory ammo, 1 flyer but it happens.
It's also about .35" away from target center, whcih was the aim point, so for me, that's a 0.345 inch group.
 
FLyer!?!?!? Shocked  where?

Lower right of the group...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 18:34
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What he didn't tell you is that one was with his eyes closed...


Mike, that is some outstanding shooting, Sir... just outstanding...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 19:44
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but he said he was having an 'off day'
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 19:46
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Yep.   Mike has forgotten more than most people will ever know about shooting.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 19:49
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and STILL knows more...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/04/2013 at 22:19
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I walk up to the target, take a look, and say: "hmmm, thats about an inch" or "half inch," or whatever it looks to reasonably be.......
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2013 at 09:16
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If I do a three round or five round grouping I use the same method... I count three or five holes and call it could. If I find one or two holes short on the target I know my grouping can be tightened up a wee bit.
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2013 at 09:36
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I look for the 2 holes closest together on the target, assume those are the real measure of my skill, approximate the distance between them, and have an impartial observer illegibly sign my target; it might have a flaw somewhere in the methods, but it works for me.

Another option, learned in the Marine Corpse, is measure by coins (I ain't as good at shooting stuff as Mike), does the group fit under a dime or a penny.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: April/10/2013 at 09:54
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Personally if i'm grouping i shoot 5 shot strings, generally waiting about a minute between each shot. 3 shot groups when getting dialed in with a new rig to zero. I never adjust without making sure i'm grouping well first. No point without doing so IMO.
 
As to measuring. i've usually done something similar to Mr McDonald, although i RARELY can group shots into a single ragged hole. I just ain't that good.
 
Have also done the coin trick as well ala RC.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2013 at 12:30
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I also do Center to Center from farthest two in my group and measure with digital calipers. But I also recently installed http://ontargetshooting.com/ since there is a 15-day free trial. My results were almost identical and it does alot more math than I can. Just scan it and identify where the bullet holes are and it does the rest. Hope this helps.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2013 at 16:44
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Oh and when shooting a Ruger one can measure the groups with a yard stick most of the time. Devil
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2013 at 18:35
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Sheesh.....GREAT shooting Mr. Mike and RC, as usual.  
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