Assuming bivariate normal distribution of impact coordinates and perfect zero, the following statements are approximately equivalent:

• mm inches 3 4 5 6 7 8 9 10 shot average group size at 7 10 25 50 100 feet yards m
• of shots in mm inches diameter target at 7 10 25 50 100 feet yards m

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• mm inches 3 4 5 6 7 8 9 10 shot average group size at 7 10 25 50 100 feet yards m
• R₉₀= , D₉₀= mm inches at 7 10 25 50 100 feet yards m

  σ= MOA= milliradians