MOA as a scoring mechanism?

[Demonic69]

Hi all
I've read up on MOA and understand it's uses when setting up your rifle.
What I don't understand is when people use it to relate to scoring/grouping. I assume, as 1 MOA is 1" at 100yds, that a 1" group at 100yds would be 1 MOA, 200yds 1/2 MOA etc?
Seems overly complicated as you could just say 1" as it's 1" whatever the distance and you don't have to mess about converting MOA to inches at different distances.
Is this an official method of measuring your grouping, are people getting confused (other than me?)

Cheers
Dean

[ovenpaa]

People tend to refer to the down range accuracy of the rifle in MOA as it is an angle so a constant however it can also be quite misleading. So many times I read of 'Genuine half minute' rifles however this often means the rifle managed to get a group of 3 shots in around a 1/2" group. This is not a true representation of the rifle/load capability unless it is a 100 yard BR rifle as you may well find when a true 5 round group is taken at 1000 yards groups closer to 18" which is approximately 1.5 MOA

Another slight issue is 1 MOA is not 1" at 100 yards although it is a good approximation.

Groups shot are invariably measured in inches with the distance declared afterwards or at least known, so 4.8"/1200 yards or .385" /100 yards. People do tend to just say it shot a .381" group and readers would probably assume that was at 100 yards.

Me, well I found a note on my iFone yesterday that says:

25 September 2010 Ulfborg 600m, 7mm once fired 3 shot group 27,0mm (To outer edges) Corrected to 20,0mm centre to centre.

It would be interesting to know what that was in MOA.

[rox]

Seems overly complicated as you could just say 1" as it's 1" whatever the distance and you don't have to mess about converting MOA to inches at different distances.

Grouping is inherently angular. If you shot a half inch group at 100 yards, it does not mean that you would have shot a half inch group if the bullets continued to 1000 yards. In very simplified terms, the shots have deviated from the path to the center of the target, and if their flight continued they would continue to deviate further from the center (when measured linearly). Staying with the hugely simplified model your 0.5" group would enlarge to a 5" group by the time it reached 1000 yards. However, what was a 0.5 minute group at 100 yards has remained a 0.5 minute group at 1000. This completely ignores ballistic effects and wind, so shooting a half minute group at 100 does not, in reality, lead to a half minute performance at 1000, but it is a lot closer than comparing 0.5" to 10". Stating any group size in inches is meaningless without knowing the distance.

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[Demonic69]

Sorry Rox, I think you read me wrong. A 1" group is a 1" group. If you were lucky enough to manage it at 1000yds it would still be a 1" group, MOA just complicates it. And, as you said, with ballistic effects and variations on rifles and ammunition used MOA just seems to get more irrelevant, unless you're wanting to make your grouping sound better; .5MOA sounds better than 1"@200yds I suppose.
Ovenpaa, I get 0.1547 MOA for that scenario, 27mm @ 600m?

I see MOA useful as a basis for measuring the deviation of your rifle/round in ideal conditions, bolted to a stand, no wind, consistent ammunition, testing at distances to see the drop of your setup.

[dromia]

A minute of angle group is not the same as adjusting your sights by minutes of angle.

[GazMorris]

A 1" group is a 1" group.

Umm, no it isnt!

Distance is critical because, as Rox correctly says, grouping is inherently angular and the use of MOA rather than pure group size allows the comparison of group sizes at different distances (although it's important to understand the limitations of this. Shooting a five shot 1/2moa group at 1200x is MUCH more impressive than shooting a five shot 1/2moa group at 1000 yards!)

Gaz

[rox]

Sorry Rox, I think you read me wrong. A 1" group is a 1" group.

Sure it is, but it doesn't tell me if it was good or bad. A 1" group at 25 yards is very bad. A 1" group at 500 yards is very good. A 1/2 minute group is good regardless of distance. That is why target dimensions scale in MOA. Sights adjust in MOA (or other angular measurement), score diagrams work in MOA, wind is called in MOA. MOA enables comparison over different distances.

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[tackb]

think in angle (moa/mil) rather than group in inches or drop in inches etc it will make corrections much easier

[Demonic69]

A minute of angle group is not the same as adjusting your sights by minutes of angle.

Are they both not using the same table of reference?

A 1" group is a 1" group.

Umm, no it isnt!

Distance is critical because, as Rox correctly says, grouping is inherently angular and the use of MOA rather than pure group size allows the comparison of group sizes at different distances (although it's important to understand the limitations of this. Shooting a five shot 1/2moa group at 1200x is MUCH more impressive than shooting a five shot 1/2moa group at 1000 yards!)

Gaz

Technically it is, you take a measuring device, measure the group and use one or another set of universally designated units, like inch or mm.
Putting it into context of how good it is at that distance is something different.
But you wouldn't say you shot 1"... you'd say you shot 1" at whatever distance, just like you'd say MOA at whatever distance

Sorry Rox, I think you read me wrong. A 1" group is a 1" group.

Sure it is, but it doesn't tell me if it was good or bad. A 1" group at 25 yards is very bad. A 1" group at 500 yards is very good. A 1/2 minute group is good regardless of distance. That is why target dimensions scale in MOA. Sights adjust in MOA (or other angular measurement), score diagrams work in MOA, wind is called in MOA. MOA enables comparison over different distances.

I suppose, if you take all of those into account, for someone completely uneducated it could make things easier, if everyone was shooting exactly the same in the same conditions. Without all of the other variables is just the same as saying 1" at 100 etc.
If you're getting 1"@100 with 25mph wind with a .22 that's pretty good, the same with a .50, not so great, so you still need the full information.

What I've read is people JUST using MOA or MOA at distance. Surely I'm not the only one that thinks that's just converting for the sake of it?

think in angle (moa/mil) rather than group in inches or drop in inches etc it will make corrections much easier

That's where I see MOA as useful and thought that was the point of it, though I may be wrong.

[rox]

I suppose, if you take all of those into account, for someone completely uneducated ...Surely I'm not the only one that thinks that's just converting for the sake of it?

To me, using MOA is one less conversion. I rarely visit the butts with a tape measure, but I can see the shot placement through a scope and plot them onto a scorecard graduated in MOA (or 'think' in MOA when looking at a target at any distance, and call wind in MOA at any distance). There are certainly situations where inches are used, e.g. beginners shooting .22 groups at 25 yards, and benchresters who measure absolute group sizes at the target, and probably hunters who must deal with a fixed size hit area regardless of distance. But I can't imagine any use for inches in multi-distance full-bore target shooting, and if that makes me uneducated I'm in good company.

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