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is this a .543" group or a .278" group?

Tim_WNC

Private
Full Member
Minuteman
Jan 4, 2014
270
234
Western NC
Stupid question maybe, but how do you measure this group? 5 shots, 100 yards, 6.5CM

Measured .543" using calipers from outside edge to outside edge.

Bullet is .264"

So...is this a .543" group or a .278" group?

7116255
 
At 100 yards an inch and an MOA are essentially the same (1 MOA = 1.047"), so your linear measurement can also be expressed as MOA.

If you had shot that group at 200 yard, your MOA would be ~ .15.

I think. :)
 
At 100 yards an inch and an MOA are essentially the same (1 MOA = 1.047"), so your linear measurement can also be expressed as MOA.

If you had shot that group at 200 yard, your MOA would be ~ .15.

I think. :)


I get the 1.047 conversion. Lefty's post quoted below confused me, but I'm pretty sure he was just wrong.


.279 center to center

.543 for MOA calculation, i.e. approximately 1/2 MOA group or .518 MOA
 
The crosshair would still have some implied movement that corresponds to the offset. The only way to really know is lock it in a vice, then the only deviation would be the mechanical accuracy of the rifle.
huh? we're saying he probbaly went .3mil up and .3mil left so he could keep the crosshair of his reticle aligned with the crosshair on the target
 
huh? we're saying he probbaly went .3mil up and .3mil left so he could keep the crosshair of his reticle aligned with the crosshair on the target
I understand what you were saying. Even with an offset, there would still be movement. No one can hold it perfectly still and a group is a group no matter where it hit.

To my original point about using the center-to-center, it has the most translative ability between calibers and shooters. It assumes we were aiming at a point and not just firing into a hole. A 2" outside edge hole means different things between a .17 mach II and a .50 bmg, but a 2" center-to-center in both is more telling. With the later, you don't have to state the caliber to understand the outcome.
 
I understand what you were saying. Even with an offset, there would still be movement. No one can hold it perfectly still and a group is a group no matter where it hit.

To my original point about using the center-to-center, it has the most translative ability between calibers and shooters. It assumes we were aiming at a point and not just firing into a hole. A 2" outside edge hole means different things between a .17 mach II and a .50 bmg, but a 2" center-to-center in both is more telling. With the later, you don't have to state the caliber to understand the outcome.
no one measures outside to outside. but sometimes its easier to measure outside to outside and subtract the caliber if you arent using the fancy new apps we have
 
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Just for clarity, not that it really matters, but this group was just used to illustrate my question. The 'offset' see here from POA is just coincidental in this case. I was doing load work up and always adjust so POA/POI are the same once I have load determined.


Annnnddd....I also ponied up for Ballistic X. Handy little app, but I wish it didn't always need a 1" reference point. Makes my usual "paper plate and a sharpie" targets less convenient.
 
You can get adhesive benchrest targets on a roll from Sinclair, or a deck of them like post-it notes from Hornady. Put your crosshairs in the box and off-set to put your groups in the bullseye center (or just print them off your computer):

7118002
7118008
 
It really doesn't matter how you measure. Group size is a nice way to test your rifle but it does more for the shooters ego than anything. Some days I shoot 1/4 moa some 1 1/4 moa, so what really is my group size, probably between 1/2 and 3/4. Just my opinion.
 
If I’m doing load development or testing the rifle / system it’s 3 shot groups.

If I’m testing myself / training, 5 shot groups.

OP, that’s a 1/4 MOA group. Good shooting
 
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