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

[Tim_WNC]

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?

 

[ForgeValley]

. 278
?

 

[pbatesaz]

.278 nice group.

 

[leftyk82]

.279 center to center

.543 for MOA calculation, i.e. approximately 1/2 MOA group or .518 MOA

 

[Tim_WNC]

. 278
?

View attachment 7116257

hey! you shorted me 2 shots... =)

Thank you.

 

[leftyk82]

Ha! Or maybe I'm just wrong.

 

[Tim_WNC]

.279 center to center

.543 for MOA calculation, i.e. approximately 1/2 MOA group or .518 MOA

And this was the cause of my question....I guess I'm confused about referencing a difference between group size as a linear measurement and its "MOA".

 

[ForgeValley]

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.

 

[Tim_WNC]

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

 

[ForgeValley]

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

Yeah, that is a 1/4 moa group.

 

[65shootmoor]

Use the center-to-center measurement, presumably it's where your crosshair was when fired.

 

[Jimgal62]

Yeah, that is a 1/4 moa group.

Agree

 

[b6graham]

Use the center-to-center measurement, presumably it's where your crosshair was when fired.

some people move a few clicks to keep a consistent POA

 

[65shootmoor]

some people move a few clicks to keep a consistent POA

Are you referring to dialing a bit of elevation so you won't punch out your aim point?

 

[stello1001]

Are you referring to dialing a bit of elevation so you won't punch out your aim point?

Yup...

 

[TheGerman]

Yes. Maybe.

 

[65shootmoor]

Yup...

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.

 

[b6graham]

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

 

[65shootmoor]

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.

 

[b6graham]

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

 

[Tim_WNC]

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.

 

[Rthur]

Nope, missing 2 shots.

R

 

[65shootmoor]

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

Someone above cited using it for moa comparison. That's what I was directing the comment toward.

 

[Tim_WNC]

Nope, missing 2 shots.

R

That’s a 5 shot group...

 

[Quest1000]

Annnnddd....I also ponied up for Ballistic X. Handy little app, but I wish it didn't always need a 1" reference point.

You can edit the reference size to any size you’d like. 10” plate etc

 

[Rthur]

That’s a 5 shot group...

Saw cavs post, strange it didn't recognize the other 2.

R

 

[ForgeValley]

Saw cavs post, strange it didn't recognize the other 2.

R

I put those 3 in manually. Assumption is the other two are within those bounds.

 

[hlee]

The hole a bullet makes in a paper target is significantly smaller than the bullet diameter. Your center to center group size is larger than 0.279"...

 

[65shootmoor]

The hole a bullet makes in a paper target is significantly smaller than the bullet diameter. Your center to center group size is larger than 0.279"...

If it was measured from center, it's correct. The center doesn't have a diameter, it's a point.

 

[hlee]

If it was measured from center, it's correct. The center doesn't have a diameter, it's a point.

That's not how it was measured. The picture shows an edge to edge diameter, and then subtracting 0.264...

 

[Deleted member 10043]

Christ, does the OP understand his .278 is the correct method?

 

[Tim_WNC]

Christ, does the OP understand his .278 is the correct method?

I do.

But we probably ought to continue with beating the horse just in case.

 

[sinister]

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):

 

[FN-Whitney]

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.

 

[HogsLife]

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

 

[65shootmoor]

That's not how it was measured. The picture shows an edge to edge diameter, and then subtracting 0.264...

My bad, misread it.