Group measurement @ 50m

O

ogion

Guest
G'day guys, I am year long time reader and 1st time writer...... I'd just like to say that I have read many posts with interest and have learnt a great deal from you guys and your experiences. So for that I thank you.

My question to you all is, how do you measure a (tight?) group size?

Yesterday I shot my best ever 5 shot group at 50m at my local range but the problem is I don't know how to measure the group. I got that software where you can scan the target and put the holes on, but I have troubles knowing exacally where to put the projectile hole template.

Can anyone please help me out?

I have attached my target for you, for reference the black bull diameter is 10.50mm or 0.413in.

Thank you in advance to anyone that can help me out. Much appreciated.
 

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Shoot one bullet off to the side, preferably in the white part of the target. Measure the OD of the black ring on the target. It will be smaller than .224. Now measure to the outside black rings on your group. Subtract the previous single hole measurment from the group outside diameter size to determine center to center group size.

Ken
 
Suggestion . . .

We can get a more accurate measurement when the group is shot in the white area of the target. Seeing the edge of the black lead/grease ring is difficult when the a shot is in the black.
 
ogion said:
G'day guys, I am year long time reader and 1st time writer...... I'd just like to say that I have read many posts with interest and have learnt a great deal from you guys and your experiences. So for that I thank you.

My question to you all is, how do you measure a (tight?) group size?

Yesterday I shot my best ever 5 shot group at 50m at my local range but the problem is I don't know how to measure the group. I got that software where you can scan the target and put the holes on, but I have troubles knowing exacally where to put the projectile hole template.

Can anyone please help me out?

I have attached my target for you, for reference the black bull diameter is 10.50mm or 0.413in.

Thank you in advance to anyone that can help me out. Much appreciated.
Click to expand...

About a .270" measuring outer edges, alot larger, probably, if using a plug with all those paper rips...................Don
 
OS to OS minus Dia of bullet

Most group measurements are measured outside edge to outside edge of the overall group. Then the diameter of the bullet is subtracted. Joe's correct, that a truer picture, could be determined if the groups were in an area other than the bull you've pictured. Your photo, only shows you are off center to the X Ring. That could cost you an X or two in a score match. Otherwise, nice group. Also, better quality target board, would give you cleaner holes.
 
Hey thanks guys, now I know why people don't shoot the bull, but only use it as a point of aim. I'll adjust my rifle to shoot low next time so I can get a better measurement. Tell me, in that group would you measure up to the tears in the paper, or just the holes? And how about the dark marks which was the bullet?
 
ogion, I measure the OD of the dark smudges and subtract the measurement of one dark smudge.:D

Ken
 
Ogion, I took a stab at it but as you pointed out it is difficult.
Target.jpg

If you are using targets that you have printed, I would suggest using card stock of at least 60 pounds, it makes better holes than regular paper.
 
Measuring groups in Sanctioned Matches . . .

Our club does not sponsor NBRSA matches any more, but when we did, we used the standard measuring device used in all NRBSA & IBS sanctioned group matches. It's called a Reticle Rule, and was first built by Mr. John Sweeny out in Washington State back in the early 1950s.

The reticle rule is a clear plastic device that attaches to a dial or digital caliper. There are at least three round circles engraved in the plastic: Usually .224, .243 and .308. You center the circle of the correct size over the left hand hole of your group. You push a pin into the target to anchor the rule, then move the rule to the right so the circle is over the shot hole farthest to the right.

I got my first one from Mr. Sweeny and later, an improved model from Manley Oakley. Both have passed on to a better place. Fred Sinclair and Robert Hart use to have them listed on their websites. Last I checked they were gone.

Neill Jones in Saegerton, Pennsylvania still makes them.
His website:
http://www.neiljones.com/html/target_measuring.html

The Jones Reticule Rule costs 80 dollars. You attached it to your dial or digital caliper. I got one of Neil's for our club 5 years ago. It's a good one. Yea: Me and the club have 3 of them now and we don''t use them any more. 5 shot GROUP matches with moving backer targets require a LOT of volunteer help. 25 shot SCORE matches are much easier to run, and the scoring gauge only costs 6 bucks.

JonesReticuleRule-1.jpg
 
Joe, I know a lot of guys here wouldn't be caught dead using software to measure group sizes but, I have been using On Target for about a year and find it very accurate and repeatable for general use. To use in a group benchrest match maybe not. But as currently a freebee for the guy at home that doesn't want to spend the money for a caliper, especially one with the fitting for $80.00, it can't be beat. I used to use a dial caliper and do the subtraction but after remeasuring the same targets with On Target, I won't go back to the calipers.
 
Thanks again guys, I downloaded On Target but I wasn't that clued up as to what I should be measuring, on previous targets they looked like a mickey mouse silhouettes so I could do them alright. Having said that I measured from the outside diameter of the holes, not the black rings, so up until now all my group measurements have been somewhat out. I know I sound like a broken record but much appreciated ay. I'll use your score MKnarr to benchmark for myself, its no competition or sheep stations or anything so I think I'll roll with that, I just needed a figure that I could aim to beat, and preferably a figure not done my me. Nice info boys.
 
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