Measuring group size.

[msaucer]

I know this may seem like a no brainer to the experienced on here - but what is the standard method of measuring group size? I see some very small groups listed on here and would like to know how they are measured.

[Ray Meketa]

Back in the good old days it was easy to measure group size. You simply measured the distance between the center of the two widest shots. Today, many groups are one ragged hole and it's impossible to identify individual shots much less the center of the two that are farthest apart. So, what you do is measure the outside of the group at it's widest or biggest point and subtract the diameter of the bullet. For example, you shoot a 30 caliber group that measures .679 at it's biggest point. .679 minus .308 will give you, hmmm lets see, 8 from 9 is 1, carry the 3, two decimals over, oh hell just use your pocket calculator and the group size comes to .371. In benchrest parlance this would be called a Big 3 and would be a very good group regardless of caliber. You don't really need a calculator unless you're ignorant like me but you probably will need a caliper that will measure in Thousandths of an inch. [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]

[ 10-28-2004: Message edited by: Cheechako ]

[ 10-28-2004: Message edited by: Cheechako ]

[Varmint Hunter]

For informal measuring of your own groups that are not one hole, just lay the jaws of a dial caliper across the centers of the two farthest bullet holes and you have it. No math required. [img]images/icons/wink.gif[/img]

For clover leaf groups or the virtual "one holer", you will need to follow Cheechako's advise. For getting accurate measurements of really tiny groups (match results) special measuring equiptment is used.

[sniper2]

What do you subtract for 6mm ??

[Tailgunner]

Sniper2
6mm=.243
6.5mm=.264
7mm=.284

[marketello]

I see a lot of shooters give their score in MOA. They aren't really figuring MOA are they, but rather measuring in inches.

Is there a formual they are using converting inches to MOA by considering the distance they are shooting?

[Ray Meketa]

Green

A MOA is actually 1.047 inches at 100 yards. But, having said that, just about everybody thinks in terms of inches even when they say MOA. So for all practical purposes, Inches and MOA are the same thing. This will probably start an arguement but it's one that has been waged many, many times before.