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side note im new to a lot of the firearm terminology, how tight/ what is a sub moa group?
Short answer:
MOA = Minute of Angle
For 100 yards "one MOA" equals to nominally 1 inch (1.047 inches to be more exact but not perfect)
For 200 yards "one MOA" equals a nominal 2 inches
For 500 yards "one MOA" equals a nominal 5 inches
For 1000 yards "one MOA" equals a nominal 10 inches (10.47 inches to be more exact)
Thus a "sub MOA" rifle shoots a group of under an inch on average.
Note:
The group sizes are measure center to center of bullet hole (muzzle loaders tend to do outside edge to far out side edge, but not many HK muzzle loaders ;-).
The group size quoted should not be the best group fired but an average (with standard deviation and/or limits) of many groups.
Also need the number of rounds in the group size and best to have an indication of the standard deviation and number of groups averaged (i.e. population)
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Long Answer:
MOA = Minute of Angle
Minute = 1/60th of a degree
360 degrees = full circle
360 degrees times 60 minutes per degree = 21,600 minutes in a full circle
full circle circumference = Pi X Diameter
Pi = 3.141592 (which goes on for ever)
Diameter = Twice the radius
Assume a radius of 100 yards (i.e. the distance the target).
100 yards time 36 inches per yard = 3600 inches for a radius or 7200 for a diameter
Thus there is 3.141592 x 3600 x 2 = 22619 inches around a circle of 100 yards in diameter.
And for a 100 yard radius one one minute subtends = 22619/21600 inches = 1.047 inches or nominally 1 inch at 100 yards