Accurate measuring of targets

horseman2

horseman2

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So how much difference does it make to get reliable measurements pertaining to group size?
Using a tape measure and believing that 13/16ths is close enough is questionable when using a 1/4 inch as a believable hole measurement.
How big is your bullet hole really? Unless using toilet paper . . . the actual size of the hole is dependant on the quality of the paper.
I have yet to measure the hole from a 22 long rifle at .224 when using card stock or something of similar quality.
Following a weekend shoot, those holes that were not encroaching on another were measured . . . and there were lots of opportunities!
It is fair to say the Lapua X-Act produced readings of .198 to .204
Rarely is the hole perfectly round as turning the measurement 90 degrees would yield different readings.
My best group of the day was .534" (o-o) at 100 metres and scored 50-5X. For ease of calculating c-c measurement, 0.200 was used giving a c-c measurement of 0.334.
Using .224 makes little difference on a group this size other than to claim a c-c of 0.310.
Using a tape measure and claiming 23/32nds equals 0.720". Subtracting .20 does not make that a less that 0.5 group any more than subtracting .224.

And now the rest of the story . . . the first shot for score on the second target was a "7"!!!:HR::HR::HR:
 
I measure from the outside edge of one hole to the inside edge of the farthest hole this automatically gives you center to center of the holes.
 
Ukrainian Wheel aka CT currently has electronic digital calipers on sale for less than $12.00.
Now you can take an accurate measurement and photograph the digital display.
That is almost a cheap as a tape rule . . . and a lot more accurate.
 
Most of the targets posted on the 1/2" group site do not subscribe and while it works for me personally (occasionally) I am not comfortable getting it to function to the print stage.

Since most guys come up with some figure that most holes will never measure I recently checked a 100 yard CZ/Brno competition on the rimfire Central site.
Attached is my target and as you see the size of the bullet holes is recorded and averaged. Note there are no "0.224" holes and there is not one that measures 0.200. Quality of paper gives accuracy.

 
Anyone interested in an actual group measuring tool? Actually made for measuring groups very easily.
Hornady calipers and Neil Jones attachment with custom magnifier with circular reticle. I just sold this to an ex customer and an excellent shooter.

IMG-0127.jpg
 
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I measure from center of hole-to-hole. For a Fudd, knowing the POI of the first shot is the most important.
 

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Finding the center of the hole is difficult when the group is one hole... that's when a magnified circular reticle and a dedicated devise shines... but it really doesn't matter for 99% of shooters.
 
IMO, Measuring C to C by eyeball is NOT very accurate. Certain to be off a few 'hairs'. I do that for my practice shots but if I were posting to CGN (only once in 100-Yd Challenge) I measure 'smear to smear' and measure the size of several holes made the same day, then subtract that from the 'Smear to Smear' measurement. I use a $20 digital and card stock and note when the unit reads into 'ten-thousandths', tho often it just does 'hundredths'.
 
horseman2 said:
So how much difference does it make to get reliable measurements pertaining to group size?
Using a tape measure and believing that 13/16ths is close enough is questionable when using a 1/4 inch as a believable hole measurement.
How big is your bullet hole really? Unless using toilet paper . . . the actual size of the hole is dependant on the quality of the paper.
I have yet to measure the hole from a 22 long rifle at .224 when using card stock or something of similar quality.
Following a weekend shoot, those holes that were not encroaching on another were measured . . . and there were lots of opportunities!
It is fair to say the Lapua X-Act produced readings of .198 to .204
Rarely is the hole perfectly round as turning the measurement 90 degrees would yield different readings.
My best group of the day was .534" (o-o) at 100 metres and scored 50-5X. For ease of calculating c-c measurement, 0.200 was used giving a c-c measurement of 0.334.
Using .224 makes little difference on a group this size other than to claim a c-c of 0.310.
Using a tape measure and claiming 23/32nds equals 0.720". Subtracting .20 does not make that a less that 0.5 group any more than subtracting .224.

And now the rest of the story . . . the first shot for score on the second target was a "7"!!!:HR::HR::HR:
Click to expand...
10 years late and still $3.00 short (thank you justinflation).
:whistle:Do they make wad cutters for .22 rimfire?
:unsure:
 
" . . . Do they make wad cutters for .22 rimfire? . . . "
Hit 'em with a file - 'Flat Nose' are supposed to be 'aero-stable' I've read :rolleyes: SK-Flat Nose were pretty accurate thru my 457 VMTR, but they quit making 'em.
 
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