MOA allows a group's physical size to be converted into an angular measurement, which makes groups fired at different distances directly comparable to one another. A group measured at 100 yards and a group measured at 300 yards can both be expressed in the same MOA terms, even though their raw measurements in inches or millimetres would look very different. That said, one group fired at 100 metres doesn't reliably predict exactly what a rifle will do at every distance within its effective range — it's a snapshot, not a guarantee.

It's worth being clear on one distinction before going further: precision describes how closely the shots group together, while accuracy describes how closely that group is centred on the intended point of impact. MOA can be used when discussing both, but group size on its own — the subject of this module — primarily measures precision.

What Is A Shot Group?

A group is a series of shots fired under reasonably consistent conditions at the same aiming point. There's no single universal minimum shot count that defines a group — the number of shots simply affects how much the group tells you.

The short version: more shots, fired consistently, tell you more. One small group tells you less than it feels like it does.

How To Measure A Group

Group size should be measured as extreme spread — the centre-to-centre distance between the two furthest-apart bullet holes.

Irregular or overlapping holes reduce how precisely this can be measured — treat the result as a close estimate rather than an exact figure in those cases.

Converting Group Size Into MOA

In plain terms, both formulas do the same thing: they work out how big your group is relative to what one full MOA actually measures at the distance you shot it. A bigger number relative to 1 MOA means a bigger group in angular terms — a smaller number means a tighter one.

Worked Example

That's a genuine sub-MOA group. But one group, on its own, doesn't prove the rifle and ammunition combination is consistently sub-MOA — it shows what happened that day, under those conditions, with that one string of shots. Consistency is demonstrated over several groups, not one.

What Determines Group Size?

Group size is the combined result of several things working together, not any single factor in isolation:

No single one of these should be assumed as the default explanation for a larger-than-expected group — a proper diagnosis looks at the whole system.

Does Group Size Expand Perfectly With Distance?

MOA gives you a useful angular comparison between distances, but real-world dispersion doesn't always scale perfectly or predictably as range increases. Wind, ammunition variation, positional stability, environmental conditions, aiming error, and shooter input can all have a larger effect at distance than the simple MOA maths alone would suggest. Testing at more than one distance — not just extrapolating from a single 100-yard or 100-metre group — gives a far more honest picture of actual performance further out.

Reading A Group Correctly

Don't adjust a zero off a single unexplained shot, or off a group that's obviously come apart for reasons unrelated to the rifle's actual capability — a called flyer, a bag shift, a gust of wind mid-string. Diagnose before you dial.

Key Takeaway