measuring group size
- Thread starter sdlonyer
- Start date
Busta Capp
CGN frequent flyer
- Location
- Town of the Blue Mountains (ON)
From centre to centre of the outside shots.
Actually, it's measure from outside to outside and subtract the size of the hole the bullet actually makes in the paper. Using bullet size is a way of cyber-shrinking, already small cyber groups.
"...claimed .250 groups..." I'd want some proof of consistency Plus the distance, the rest used and the bullet used. One such group, at 25 yards, doesn't count. It'd be a miracle with most hunting rifles using hunting bullets.
Outside to outside is enough. Subtracting the bullet diameter or the hole it makes gives you the POI of the group. Handy thing to know for adjusting the sights.
Outside to outside is enough. Subtracting the bullet diameter or the hole it makes gives you the POI of the group. Handy thing to know for adjusting the sights.
to achieve a .25 minute group even using a laser beam would require a cumulative aiming and trigger control error of 1/4000ths of an inch at muzzle. Any math major feel free to chim in if my calculations are incorrect.
This would allow an aiming error at muzzle of 1/16th of the width of a human hair. I have shot some decent groups, but they are not really indicative of my rifle, my load, and my skill level. The five rounds have to land somewhere.
This would allow an aiming error at muzzle of 1/16th of the width of a human hair. I have shot some decent groups, but they are not really indicative of my rifle, my load, and my skill level. The five rounds have to land somewhere.
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Groups
Groups are measured from center to center. This also will give you the center of your group if you triangulate your 3 or 5 shots.
Center to center is measured by the outside of your two farthest rounds and then subtracting the bullets diameter.
Made simple!
Groups are measured from center to center. This also will give you the center of your group if you triangulate your 3 or 5 shots.
Center to center is measured by the outside of your two farthest rounds and then subtracting the bullets diameter.
Made simple!
oh yeah forsure a .30 cal only leaves a .270 hole????????lmao Dream on
outside to outside minus bullet diameter unless you can figure out exactly where the center of the hole is!
Besides if you shoot a great grouping pat yourself on the back, does not make your pee pee bigger on the net!
Go ahead and measure some targets if you don't believe me.The paper often stretches slightly,the result being a slightly smaller hole with a greyish ring around the hole.If you measure to the outside edges of the greyish ring,you usually end up much closer to the bullet diameter.
Try this if you want to be accurate... http://www.ontargetshooting.com/index.html Just take a picture of your group with a ruler held against the target.
burnt_servo
CGN Ultra frequent flyer
- Location
- right in the middle of b.c.
+1
and i'll add , how many shots where fired ?
tiny 3 shot groupings can be easily done ,
tiny 5 shot groups are much much harder to do .
Just do what most do on this site, measure from centre to centre of your 2 furthest apart shots, if it is over 1", subtract 1", that is your group size, similarly; if it is over 1/2", subtract 1/2". You'll find that you are shooting with the best of them very quickly.
X2
This is a great program, here is an example of a group I shot tonite at 500m
The only thing I don't like about the program is its inability to allow input in metric. It does have a few pre-sets in meters but if you shoot other distances then you have to convert to yds. The Reference setting (using a ruler in the picture or a known size grid or ring) is also in standard so must be entered in inches hence the 546.8yd Distance
3rd hole from the left and the one hole touching the white line both measure .262 (.264 bullet). The only time the actual bullet hole size would come into play would be during a Benchrest Match.
For measuring groups, subtracting the bullet diameter is sufficient.
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You do subtract the actual bullet diameter in all cases,the smaller holes effect the results when measuring across the outsides of the farthest two holes.Depending on the bullet,the target,and on the backing,the bullet hole may or may not be the same diameter as the bullet.I have several targets where the bullet holes are up to .050" smaller than the actual bullet diameter.That makes an actual .300" group measure only .250".I just measure to the edges of the dark rings around the holes,and I end up with the proper measurement.
